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Sample records for antithrombin recombinant atryn

  1. Use of recombinant human antithrombin concentrate in pregnancy

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    Baumann Kreuziger LM

    2013-09-01

    Full Text Available Lisa M Baumann Kreuziger,1 Tracy L Prosen,2 Mark T Reding1 1Division of Hematology, Oncology, and Transplantation, University of Minnesota, MN, USA; 2Obstetrics and Gynecology, Maternal Fetal Medicine Center, University of Minnesota, MN, USAWe read with great interest James et al’s article "Prevention and treatment of venous thromboembolism in pregnancy in patients with hereditary antithrombin deficiency." The authors reported a case series of six women with antithrombin (AT deficiency treated with plasma derived antithrombin concentrate (pdAT; Thrombate III®, Grifols Therapeutics, Clayton, NC, USA.1 In contrast to these cases, we have managed three AT-deficient women over the past two years with low-molecular-weight-heparin during pregnancy and recombinant human antithrombin concentrate (rhAT; ATryn®, GTC Biotherapeutics, Framingham, MA, USA at delivery. In the Phase III trial leading to approval of rhAT, pregnant women required frequent dose modifications, and an alternate dosing regimen is currently recommended by the manufacturer.2,3 The detailed information provided in these cases may assist future providers in managing pregnant patients with AT deficiency.View original paper by James and colleagues.

  2. Neuraxial anesthesia for labor and cesarean delivery in a parturient with hereditary antithrombin deficiency on recombinant human antithrombin infusion therapy.

    Science.gov (United States)

    Pamnani, Anup; Rosenstein, Megan; Darwich, Alaeldin; Wolfson, Alexander

    2010-09-01

    A recombinant human antithrombin (rhAT; generic name: antithrombin Alfa) has recently been developed. A 37 year-old parturient with hereditary antithrombin deficiency, receiving rhAT infusion therapy, who successfully received an epidural catheter for analgesia and anesthesia during labor and cesarean delivery, is presented. PMID:20868967

  3. Rapid high-performance liquid chromatographic quantification of recombinant human antithrombin III during production and purification

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    Büntemeyer, Heino; Tebbe, H.; Lütkemeyer, Dirk; Lehmann, Jürgen

    1994-01-01

    For monitoring of recombinant human antithrombin III during cell culture processes and subsequent purification steps a rapid method for quantitative determination was developed. The need for the introduction of this rapid method came from the limited availability of a quantitative enzyme-linked immunosorbent assay (ELISA) and the very time-consuming ELISA procedure. The developed method is based on reversed-phase high-performance liquid chromatography using a C 4 column. The separation by gra...

  4. Antithrombin III (AT and recombinant tissue plasminogen activator (R-TPA used singly and in combination versus supportive care for treatment of endotoxin-induced disseminated intravascular coagulation (DIC in the neonatal pig

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    Gardner Renee'

    2006-05-01

    Full Text Available Abstract Background Disseminated intravascular coagulation (DIC is a pathological disturbance of the complex balance between coagulation and anticoagulation that is precipitated by vascular injury, acidosis, endotoxin release and/or sepsis and characterized by severe bleeding and excessive clotting. The innately low levels of coagulation factors found in newborn infants place them at extremely high risk for DIC. Anecdotal reports suggest that either anticoagulant or fibrinolytic therapy may alleviate some of the manifestations of DIC. To test the hypothesis that replacement of both anticoagulants and fibrinolytics may improve survival and outcome better than either single agent or supportive care alone, we utilized a neonatal piglet model of endotoxin-induced DIC. Methods DIC was induced in twenty-seven neonatal pigs (7 to 14 days of age by intravenous administration of E. coli endotoxin (800 μg/kg over 30 min. The piglets were divided into 4 groups on the basis of treatment protocol [A: supportive care alone; B: Antithrombin III (AT, 50 μg/kg bolus, 25 μg/kg per hr continuous infusion and supportive care; C: Recombinant Tissue Plasminogen Activator (R-TPA, 25 μg/kg per hr continuous infusion and supportive care; D: AT, R-TPA and supportive care] and monitored for 3 primary outcome parameters (survival time, macroscopic and microscopic organ involvement and 4 secondary outcome parameters (hematocrit; platelet count; fibrinogen level; and antithrombin III level. Results Compared with supportive care alone, combination therapy with AT and R-TPA resulted in a significant improvement of survival time, hematocrit, AT level, macroscopic and microscopic organ involvement, p Conclusion The findings suggest that combining AT, R-TPA and supportive care may prove more advantageous in treating the clinical manifestations of DIC in this neonatal pig model than either single modality or supportive care alone.

  5. Antithrombin deficiency in pregnancy.

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    Durai, Shivani; Tan, Lay Kok; Lim, Serene

    2016-01-01

    We present a case of a 39-year-old, gravida 3 para 2, Chinese female with a history of inherited type 1 Antithrombin deficiency and multiple prior episodes of venous thromboembolism. She presented at 29+4 weeks' gestation with severe pre-eclampsia complicated by haemolysis, elevated liver enzymes and low platelet (HELLP) syndrome. She subsequently underwent an emergency caesarean section for non-reassuring fetal status, which was complicated by postpartum haemorrhage secondary to uterine atony, requiring a B-Lynch suture intraoperatively. PMID:27207982

  6. Antithrombin Dublin (p.Val30Glu)

    DEFF Research Database (Denmark)

    Navarro-Fernandez, José; de la Morena-Barrio, María Eugenia; Padilla, José; Miñano, Antonia; Bohdan, Nataliya; Águila, Sonia; Martínez-Martínez, Irene; Sevivas, Teresa S; de Cos, Carmen; Fernández-Mosteirín, Nuria; Llamas, Pilar; Asenjo, Susana; Medina, Pilar; Souto, Juan Carlos; Overvad, Kim; Kristensen, Søren R; Corral, Javier; Vicente, Vicente

    2016-01-01

    The key haemostatic role of antithrombin and the risk of thrombosis associated with its deficiency support that the low incidence of antithrombin deficiency among patients with thrombosis might be explained by underestimation of this disorder. It was our aim to identify mutations in SERPINC1 caus...

  7. Antithrombin in the treatment of burn trauma.

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    Kowal-Vern, Areta; Orkin, Bruce A

    2016-02-01

    Antithrombin (AT) is a natural anticoagulant with anti-inflammatory properties that has demonstrated value in sepsis, disseminated intravascular coagulation and in burn and inhalation injury. With high doses, AT may decrease blood loss during eschar excision, reducing blood transfusion requirements. There are no human randomized, placebo-controlled studies, which have tested the true benefit of this agent in these conditions. Two main forms of AT are either plasma-derived AT (phAT) and recombinant AT (rhAT). Major ovine studies in burn and smoke inhalation injury have utilized rhAT. There have been no studies which have either translated the basic rhAT research in burn trauma, or determined the tolerance and pharmacokinetics of rhAT concentrate infusions in burn patients. Advantages of rhAT infusions are no risk of blood borne diseases and lower cost. However, the majority of human burn patient studies have been conducted utilizing phAT. Recent Japanese clinical trials have started using phAT in abdominal sepsis successfully. This review examines the properties of both phAT and rhAT, and analyzes studies in which they have been utilized. We believe that it is time to embark on a randomized placebo-controlled multi-center trial to establish the role of AT in both civilian and military patients with burn trauma. PMID:26855890

  8. Antithrombin, an Important Inhibitor in Blood Clots.

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    Zhu, Ying; Cong, Qing-Wei; Liu, Yue; Wan, Chun-Ling; Yu, Tao; He, Guang; He, Lin; Cai, Lei; Chou, Kuo-Chen

    2016-01-01

    Blood coagulation is healthy and lifesaving because it can stop bleeding. It can, however, be a troublemaker as well, causing serious medical problems including heart attack and stroke. Body has complex blood coagulation cascade to modulate the blood clots. In the environment of plasma, the blood coagulation cascade is regulated by antithrombin, which is deemed one of the most important serine protease inhibitors. It inhibits thrombin; it can inhibit factors IXa and Xa as well. Interestingly, its inhibitory ability will be significantly increased with the existence of heparin. In this minireview paper, we are to summarize the structural features of antithrombin, as well as its heparin binding modes and anti-coagulation mechanisms, in hopes that the discussion and analysis presented in this paper can stimulate new strategies to find more effective approaches or compounds to modulate the antithrombin. PMID:26411319

  9. Generation of Humanized Mouse Models with Focus on Antithrombin Deficiency

    DEFF Research Database (Denmark)

    Jensen, Astrid Bøgh

    2015-01-01

    Antithrombin is one of the major inhibitors of the coagulation cascade. Antithrombin deficiency in humans significantly increases the risk of thrombosis. Mice homozygous for an antithrombin knock out die at day 16.5 of gestation, due to disseminated intravascular coagulation and organ failure. I ...

  10. Antithrombin III for critically ill patients

    DEFF Research Database (Denmark)

    Afshari, Arash; Wetterslev, Jørn; Brok, Jesper Sune;

    2008-01-01

    Critical illness is associated with uncontrolled inflammation and vascular damage which can result in multiple organ failure and death. Antithrombin III (AT III) is an anticoagulant with anti-inflammatory properties but the efficacy and any harmful effects of AT III supplementation in critically ...

  11. Antithrombin III Basel. Identification of a Pro-Leu substitution in a hereditary abnormal antithrombin with impaired heparin cofactor activity.

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    Chang, J Y; Tran, T H

    1986-01-25

    Antithrombin III Basel is a hereditary abnormal antithrombin with normal progressive inhibition activity (normal reactive site) and reduced heparin cofactor activity (impaired heparin binding site). Structures of antithrombin III Basel and normal antithrombin III isolated from the same patient were compared by peptide mapping using the dimethylaminoazobenzene isothiocyanate precolumn derivatization technique. Of the approximately 50 tryptic peptides of normal and abnormal antithrombin III, one peptide comprising residues 40-46 had a different retention time in reversed-phase high performance liquid chromatography. The amino acid sequence of the peptide from antithrombin III Basel had a single substitution of Pro (normal) by Leu (abnormal) at position 41. This substitution is close to an Arg (residue 47) and a Trp (residue 49) which have previously been shown to be critical for heparin binding by antithrombin III. Although additional amino acid substitutions in antithrombin III Basel cannot be ruled out, this Pro-Leu replacement could cause a conformational change by increasing both the helical structure and the hydrophobicity around residue 41. These data suggest that: (i) the heparin binding site of antithrombin III encompasses the region containing residues 41, 47, and 49; and (ii) the impaired heparin cofactor activity of antithrombin III Basel is likely due to a conformational change of the heparin binding site induced by the Pro-Leu substitution at position 41. PMID:3080419

  12. 21 CFR 864.7060 - Antithrombin III assay.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Antithrombin III assay. 864.7060 Section 864.7060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... assay. (a) Identification. An antithrombin III assay is a device that is used to determine the...

  13. Increased N-glycosylation efficiency by generation of an aromatic sequon on N135 of antithrombin.

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    Sonia Aguila

    Full Text Available The inefficient glycosylation of consensus sequence on N135 in antithrombin explains the two glycoforms of this key anticoagulant serpin found in plasma: α and β, with four and three N-glycans, respectively. The lack of this N-glycan increases the heparin affinity of the β-glycoform. Recent studies have demonstrated that an aromatic sequon (Phe-Y-Asn-X-Thr in reverse β-turns enhances N-glycosylation efficiency and stability of different proteins. We evaluated the effect of the aromatic sequon in this defective glycosylation site of antithrombin, despite of being located in a loop between the helix D and the strand 2A. We analyzed the biochemical and functional features of variants generated in a recombinant cell system (HEK-EBNA. Cells transfected with wild-type plasmid (K133-Y-N135-X-S137 generated 50% of α and β-antithrombin. The S137T, as previously reported, K133F, and the double mutant (K133F/S137T had improved glycosylation efficiency, leading to the secretion of α-antithrombin, as shown by electrophoretic and mass analysis. The presence of the aromatic sequon did not significantly affect the stability of this conformationally sensitive serpin, as revealed by thermal denaturation assay. Moreover, the aromatic sequon hindered the activation induced by heparin, in which is involved the helix D. Accordingly, K133F and particularly K133F/S137T mutants had a reduced anticoagulant activity. Our data support that aromatic sequons in a different structural context from reverse turns might also improve the efficiency of N-glycosylation.

  14. Sulfated cellulose thin films with antithrombin affinity

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    2009-11-01

    Full Text Available Cellulose thin films were chemically modified by in situ sulfation to produce surfaces with anticoagulant characteristics. Two celluloses differing in their degree of polymerization (DP: CEL I (DP 215–240 and CEL II (DP 1300–1400 were tethered to maleic anhydride copolymer (MA layers and subsequently exposed to SO3•NMe3 solutions at elevated temperature. The impact of the resulting sulfation on the physicochemical properties of the cellulose films was investigated with respect to film thickness, atomic composition, wettability and roughness. The sulfation was optimized to gain a maximal surface concentration of sulfate groups. The scavenging of antithrombin (AT by the surfaces was determined to conclude on their potential anticoagulant properties.

  15. Antithrombin III for critically ill patients

    DEFF Research Database (Denmark)

    Allingstrup, Mikkel; Wetterslev, Jørn; Ravn, Frederikke B;

    2016-01-01

    BACKGROUND: Critical illness is associated with uncontrolled inflammation and vascular damage which can result in multiple organ failure and death. Antithrombin III (AT III) is an anticoagulant with anti-inflammatory properties but the efficacy and any harmful effects of AT III supplementation in......, moderate quality of evidence) in the AT III group. The amount of red blood cells administered had a mean difference (MD) of 138.49 (95% Cl -391.35 to 668.34, I² statistic = 84%, random-effect model, 4 trials, 137 participants, very low quality of evidence). The effect of AT III in patients with multiple...... organ failure (MOF) was a MD of -1.24 (95% Cl -2.18 to -0.29, I² statistic = 48%, random-effects model, 3 trials, 156 participants, very low quality of evidence) and for patients with an Acute Physiology and Chronic Health Evaluation score (APACHE) at II and III the MD was -2.18 (95% Cl -4.36 to -0...

  16. Magnetic particles as affinity matrix for purification of antithrombin

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    Mercês, A. A. D.; Maciel, J. C.; Carvalho Júnior, L. B.

    2015-11-01

    Immobilization of biomolecules onto insoluble supports is an important tool for the fabrication of a diverse range of functional materials. It provides advantages: enhanced stability and easy separation. In this work two different magnetic composites were synthesized (MAG-PANI-HS and mDAC-HS) to human antithrombin purification. The magnetic particles (MAG) were obtained by co-precipitation method of iron salts II and III and subsequently coated with polyaniline (MAG-PANI particles). Dacron (polyethylene terephthalate) suffered a hydrazinolysis reaction to obtain a powder (Dacron hydrazide) which was subsequently magnetized (mDAC particles) also by co-precipitation method. Heparan sulfate (HS) was immobilized to MAG-PANI and mDAC retained respectively 35μg and 38.6μg per of support. The magnetic composite containing HS immobilized (MAG-PANI-HS and mDAC-HS) was incubated with human blood plasma (1mL) and then washed with NaCl gradients. Electrophoresis of proteins present in eluates showed bands of antithrombin (58kDa). A reduction in the antithrombin activity was detected in plasma that were incubated in the composites magnetic with HS immobilized, suggesting that the antithrombin was removed of the human blood plasma and then purified. Therefore, the above results suggest that both preparations: MAG-PANI-HS and mDAC-HS are able to affinity purify antithrombin, an important component of blood coagulation.

  17. Antithrombin III for critically ill patients

    DEFF Research Database (Denmark)

    Allingstrup, Mikkel; Wetterslev, Jørn; Ravn, Frederikke B.;

    2016-01-01

    PURPOSE: Antithrombin III (AT III) is an anticoagulant with anti-inflammatory properties. We assessed the benefits and harms of AT III in critically ill patients. METHODS: We searched from inception to 27 August 2015 in CENTRAL, MEDLINE, EMBASE, CAB, BIOSIS and CINAHL. We included randomized cont...

  18. Inherited antithrombin deficiency and anabolic steroids: a risky combination.

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    Choe, Hannah; Elfil, Mohamed; DeSancho, Maria T

    2016-09-01

    A 20-year-old male with asymptomatic inherited type 1 antithrombin deficiency and a family history of thrombosis started injecting himself with testosterone 250 mg intramuscularly twice weekly for 5 weeks. He presented to the hospital with progressive dyspnea on exertion, chest pain and hemoptysis. Workup revealed bilateral submassive pulmonary embolism and proximal right lower extremity deep vein thrombosis. He was treated with intravenous (IV) unfractionated heparin and underwent catheter-directed thrombolysis with alteplase to the main pulmonary arteries. Postprocedure, he remained on IV alteplase infusion for 24 h and unfractionated heparin in the intensive care unit. Concomitantly he received plasma-derived antithrombin concentrate. He was transitioned to subcutaneous enoxaparin twice daily and discharged from the hospital on oral rivaroxaban 15 mg twice a day. This case highlights the heightened thrombogenic effect of anabolic steroids in the setting of underlying thrombophilia especially in younger subjects. PMID:26588446

  19. Interaction of antithrombin III with preadsorbed albumin-heparin conjugates

    OpenAIRE

    Hennink, W.E.; Ebert, C.D.; Kim, S. W.; Breemhaar, W.; Bantjes, A.; Feijen, J.

    1984-01-01

    The adsorption of antithrombin III (AT III) onto polystyrene surfaces preadsorbed with albumin or albuminheparin conjugates was studied using a two step enzyme immuno assay. When AT III-buffer solutions were used, the highest adsorption values were measured on high affinity albumin-heparin conjugate pretreated surfaces. Less AT III adsorption was found on nonfractionated albumin-heparin conjugate preadsorbed surfaces. AT III adsorption could also be detected on low affinity conjugate and albu...

  20. Antithrombin controls tumor migration, invasion and angiogenesis by inhibition of enteropeptidase

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    Luengo-Gil, Ginés; Calvo, María Inmaculada; Martín-Villar, Ester; Águila, Sonia; Bohdan, Nataliya; Antón, Ana I.; Espín, Salvador; Ayala de la Peña, Francisco; Vicente, Vicente; Corral, Javier; Quintanilla, Miguel; Martínez-Martínez, Irene

    2016-01-01

    Antithrombin is a key inhibitor of the coagulation cascade, but it may also function as an anti-inflammatory, anti-angiogenic, anti-viral and anti-apoptotic protein. Here, we report a novel function of antithrombin as a modulator of tumor cell migration and invasion. Antithrombin inhibited enteropeptidase on the membrane surface of HT-29, A549 and U-87 MG cells. The inhibitory process required the activation of antithrombin by heparin, and the reactive center loop and the heparin binding domain were essential. Surprisingly, antithrombin non-covalently inhibited enteropeptidase, revealing a novel mechanism of inhibition for this serpin. Moreover, as a consequence of this inhibition, antithrombin was cleaved, resulting in a molecule with anti-angiogenic properties that reduced vessel-like formation of endothelial cells. The addition of antithrombin and heparin to U-87 MG and A549 cells reduced motility in wound healing assays, inhibited the invasion in transwell assays and the degradation of a gelatin matrix mediated by invadopodia. These processes were controlled by enteropeptidase, as demonstrated by RNA interference experiments. Carcinoma cell xenografts in nude mice showed in vivo co-localization of enteropeptidase and antithrombin. Finally, treatment with heparin reduced experimental metastasis induced by HT29 cells in vivo. In conclusion, the inhibition of enteropeptidase by antithrombin may have a double anti-tumor effect through inhibiting a protease involved in metastasis and generating an anti-angiogenic molecule. PMID:27270881

  1. Discordant diagnoses obtained by different approaches in antithrombin mutation analysis

    DEFF Research Database (Denmark)

    Feddersen, Søren; Nybo, Mads

    OBJECTIVES: In hereditary antithrombin (AT) deficiency it is important to determine the underlying mutation since the future risk of thromboembolism varies considerably between mutations. DNA investigations are in general thought of as flawless and irrevocable, but the diagnostic approach can be...... critical. We therefore investigated mutation results in the AT gene, SERPINC1, with two different approaches. DESIGN AND METHODS: Sixteen patients referred to the Centre for Thrombosis and Haemostasis, Odense University Hospital, with biochemical indications of AT deficiency, but with a negative denaturing...... high-performance liquid chromatography (DHPLC) mutation screening (routine approach until recently) were included. As an alternative mutation analysis, direct sequencing of all exons and exon-intron boundaries without pre-selection by DHPLC was performed. RESULTS: Out of sixteen patients with a...

  2. Antithrombin gene Arg197Stop mutation-associated venous sinus thrombosis in a Chinese family

    Institute of Scientific and Technical Information of China (English)

    Ang Li; Dexin Wang; Qiming Xue; Baoen Wang; Tianhui Liu; Zhandong Liu; Jimei Li; Chunling Zhang; Jun Chen; Jinmei Sun; YanfeiHan; Lili Wang

    2011-01-01

    This study sought to elucidate the genetic correlation of cerebral venous sinus thrombosis caused by a hereditary antithrombin deficiency in a Chinese family, at the genetic and protein levels. A nonsense mutation from C to T on locus 6431 in exon 3B of the antithrombin gene was observed,leading to an arginine (CGA) to stop codon (TGA) change in the protein. This is the first report of this mutation in China. Ineffective heparin therapy in the propositus patient is associated with a lack of heparin binding sites after antithrombin gene mutation. Characteristic low intracranial pressure in the acute phase might be specific to this patient with cerebral venous sinus thrombosis.

  3. Antithrombin can modulate coagulation, cytokine production, and expression of adhesion molecules in abdominal aortic aneurysm repair surgery.

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    Nishiyama, Tomoki

    2006-04-01

    We investigated the effects of antithrombin on coagulation, fibrinolysis, and production of cytokines and adhesion molecules in abdominal aortic aneurysm repair surgery. Sixteen patients for Y-shaped graft replacement of abdominal aortic aneurysm were divided into an antithrombin group and a control group. In the antithrombin group, 3000 U antithrombin was infused over 30 min before heparin administration and 24 h later. White blood cell counts, platelet counts, prothrombin time ratio, and serum concentrations of antithrombin, polymorphonuclear leukocyte elastase, interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor-alpha, and adhesion molecules, and variables of coagulation and fibrinolysis were measured before surgery, at the end of surgery, and 1 and 2 days after surgery. The antithrombin concentration decreased in the control group, whereas it increased in the antithrombin group with significant differences between the groups. Prothrombin time ratio, concentrations of d-dimer, thrombin-antithrombin complex, and intercellular adhesion molecule-1 increased only in the control group and polymorphonuclear leukocyte elastase, IL-6, tumor necrosis factor-alpha, and vascular cell adhesion molecule-1 increased in both groups. They were significantly less in the antithrombin group except for intercellular adhesion molecule-1. In conclusion, antithrombin could decrease hypercoagulation and inflammatory activation during abdominal aortic aneurysm surgery, which may decrease adverse events. PMID:16551889

  4. Activation of antithrombin III isoforms by heparan sulphate glycosaminoglycans and other sulphated polysaccharides.

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    Carlson, T H; Kolman, M R; Piepkorn, M

    1995-07-01

    Antithrombin III occurs naturally as two functionally distinct molecular species that differ in glycosylation at Asn135. Whereas the predominant, glycosylated isoform has high affinity for heparin, a quantitatively minor isoform lacking glycosylation at that site displays relatively higher affinity for both heparins and heparinoids. We characterized the ability of various sulphated polysaccharides to potentiate the rates of thrombin inhibition by the isoforms. High-molecular-weight dextran sulphate was the most effective of those studied, increasing thrombin inhibition by the higher-affinity antithrombin III isoform up to five-fold more efficiently than did heparin fractions with low-affinity for antithrombin III. In addition, dextran sulphate activated the higher-affinity isoform as much as twelve times more effectively than it did the lower-affinity isoform. Pentosan polysulphate was up to three-fold, and some heparan sulphate fractions up to two-fold, more effective with the higher, compared with the lower affinity, isoform. Heparan sulphate preparations less effectively increased the rate of thrombin inhibition than did the other low-affinity polysaccharides. Structure-function studies indicated positive correlations between activity and both polymer length and anionic group density of low-affinity sulphated polysaccharides. The observed effects of the heparan sulphates on this anticoagulant pathway, although of low potency, are consistent with the hypotheses that these substances naturally regulate blood homeostasis in vascular tissues and that much of this function may be mediated by the higher-affinity antithrombin III isoform. PMID:8589216

  5. Anticoagulant and anti-inflammatory effects after peritoneal lavage with antithrombin in experimental polymicrobial peritonitis

    NARCIS (Netherlands)

    S.Q. van Veen; C.W. Cheung; J.C.M. Meijers; T.M. van Gulik; M.A. Boermeester

    2006-01-01

    Background: In sepsis, coagulation inhibition using high-dose systemic antithrombin (AT) tends to improve survival. However, systemic AT use is complicated by increased risk of bleeding (odds ratio 1,7) and clinically important survival increase is seen only in the non-heparinized subgroup. Local (i

  6. Antithrombin inhibits bronchoalveolar activation of coagulation and limits lung injury during Streptococcus pneumoniae pneumonia in rats

    NARCIS (Netherlands)

    Choi, Goda; Hofstra, Jorrit-Jan H; Roelofs, Joris J T H; Rijneveld, Anita W; Bresser, Paul; van der Zee, Jaring S; Florquin, Sandrine; van der Poll, Tom; Levi, Marcel; Schultz, Marcus J

    2008-01-01

    OBJECTIVE: Alveolar fibrin deposition is a hallmark of pneumonia. It has been proposed that natural inhibitors of coagulation, including activated protein C, antithrombin, and tissue factor pathway inhibitor, exert lung-protective effects via anticoagulant and possibly anti-inflammatory pathways. We

  7. Regions flanking exon 1 regulate constitutive expression of the human antithrombin gene.

    Science.gov (United States)

    Fernandez-Rachubinski, F A; Weiner, J H; Blajchman, M A

    1996-11-15

    We have identified cis-acting elements and trans-acting factors that regulate constitutive expression of the human antithrombin gene. The activity of the sequences flanking the first exon of the gene was investigated using a luciferase-based reporter assay in transiently transfected HepG2, COS1, BSC40, and HeLa cells. Deletion analysis allowed the mapping of two elements able to promote antithrombin gene transcription in HepG2 and COS1 cells. The first element is located upstream of the first exon (-150/+68 nucleotides). The second element is in the first intervening sequence (+300/+700 nucleotides) and functions in an orientation opposite to that of the first. Footprint analysis showed three protected areas in the 5' upstream element at -92/-68 (element A), -14/+37 (element B), and -126/-100 nucleotides (element C). These elements acted as enhancers in luciferase reporter assays. Gel retardation analysis demonstrated that two liver-enriched transcription factors, hepatocyte nuclear factor 4 (HNF4) and CCAAT enhancer-binding protein (C/EBPa), bound to the 5' upstream element. HNF4 bound to elements A and C, whereas C/EBPa bound to element B. Element A also interacted with the ubiquitous nuclear hormone receptors chicken ovalbumin upstream promoter transcription factor 1 (COUP-TF1), thyroid hormone receptor alpha (TRalpha), peroxisome proliferator-activated receptor alpha(PPARalpha), and retinoid X receptor alpha (RXRalpha). In HepG2 and BSC40 cells, HNF4, C/EBPalpha, and RXRalpha activated luciferase expression from a reporter construct containing the 5'-upstream minimal antithrombin gene promoter, while COUP-TF1, TRalpha, and HNF3 (alpha or beta) repressed such expression. Our results show that constitutive expression of the human antithrombin gene depends in part upon the interplay of these transcription factors and suggest that signaling pathways regulated by these factors can modulate antithrombin gene transcription. PMID:8910619

  8. Antithrombin significantly influences platelet adhesion onto immobilized fibrinogen in an in-vitro system simulating low flow

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    Scharf Rüdiger E

    2006-10-01

    Full Text Available Abstract Background Adhesion of platelets onto immobilized fibrinogen is of importance in initiation and development of thrombosis. According to a recent increase in evidence of a multiple biological property of antithrombin, we evaluated the influence of antithrombin on platelet adhesion onto immobilized fibrinogen using an in-vitro flow system. Methods Platelets in anticoagulated whole blood (29 healthy blood donors were labelled with fluorescence dye and perfused through a rectangular flow chamber (shear rates of 13 s-1 to 1500 s-1. Platelet adhesion onto fibrinogen-coated slips was assessed using a fluorescence laser-scan microscope and compared to the plasma antithrombin activity. Additionally the effect of supraphysiological AT supplementation on platelets adhesion rate was evaluated. Results Within a first minute of perfusion, an inverse correlation between platelet adhesion and plasma antithrombin were observed at 13 s-1 and 50 s-1 (r = -0.48 and r = -0.7, p -1, within first minute have been found. An in-vitro supplementation of whole blood with antithrombin increased the antithrombin activity up to 280% and platelet adhesion rate reached about 65% related to the adhesion rate in a non-supplemented blood (1.25 ± 0.17 vs. 1.95 ± 0.4 p = 0.008, respectively. Conclusion It appears that antithrombin in a low flow system suppresses platelet adhesion onto immobilized fibrinogen independently from its antithrombin activity. A supraphysiological substitution of blood with antithrombin significantly reduces platelet adhesion rate. This inhibitory effect might be of clinical relevance.

  9. Identification of antithrombin-modulating genes. Role of LARGE, a gene encoding a bifunctional glycosyltransferase, in the secretion of proteins?

    Directory of Open Access Journals (Sweden)

    María Eugenia de la Morena-Barrio

    Full Text Available The haemostatic relevance of antithrombin together with the low genetic variability of SERPINC1, and the high heritability of plasma levels encourage the search for modulating genes. We used a hypothesis-free approach to identify these genes, evaluating associations between plasma antithrombin and 307,984 polymorphisms in the GAIT study (352 individuals from 21 Spanish families. Despite no SNP reaching the genome wide significance threshold, we verified milder positive associations in 307 blood donors from a different cohort. This validation study suggested LARGE, a gene encoding a protein with xylosyltransferase and glucuronyltransferase activities that forms heparin-like linear polysaccharides, as a potential modulator of antithrombin based on the significant association of one SNPs, rs762057, with anti-FXa activity, particularly after adjustment for age, sex and SERPINC1 rs2227589 genotype, all factors influencing antithrombin levels (p = 0.02. Additional results sustained this association. LARGE silencing inHepG2 and HEK-EBNA cells did not affect SERPINC1 mRNA levels but significantly reduced the secretion of antithrombin with moderate intracellular retention. Milder effects were observed on α1-antitrypsin, prothrombin and transferrin. Our study suggests LARGE as the first known modifier of plasma antithrombin, and proposes a new role for LARGE in modulating extracellular secretion of certain glycoproteins.

  10. Mechanism of poly(acrylic acid) acceleration of antithrombin inhibition of thrombin: implications for the design of novel heparin mimics.

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    Monien, Bernhard H; Cheang, Kai I; Desai, Umesh R

    2005-08-11

    The bridging mechanism of antithrombin inhibition of thrombin is a dominant mechanism contributing a massive approximately 2500-fold acceleration in the reaction rate and is also a key reason for the clinical usage of heparin. Our recent study of the antithrombin-activating properties of a carboxylic acid-based polymer, poly(acrylic acid) (PAA), demonstrated a surprisingly high acceleration in thrombin inhibition (Monien, B. H.; Desai, U. R. J. Med. Chem. 2005, 48, 1269). To better understand this interesting phenomenon, we have studied the mechanism of PAA-dependent acceleration in antithrombin inhibition of thrombin. Competitive binding studies with low-affinity heparin and a heparin tetrasaccharide suggest that PAA binds antithrombin in both the pentasaccharide- and the extended heparin-binding sites, and these results are corroborated by molecular modeling. The salt-dependence of the K(D) of the PAA-antithrombin interaction shows the formation of five ionic interactions. In contrast, the contribution of nonionic forces is miniscule, resulting in an interaction that is significantly weaker than that observed for heparins. A bell-shaped profile of the observed rate constant for antithrombin inhibition of thrombin as a function of PAA concentration was observed, suggesting that inhibition proceeds through the "bridging" mechanism. The knowledge gained in this mechanistic study highlights important rules for the rational design of orally available heparin mimics. PMID:16078853

  11. Domain structure of antithrombin III. Tentative localization of the heparin binding region using 1H NMR spectroscopy

    International Nuclear Information System (INIS)

    The denaturation of human and bovine antithrombin III by guanidine hydrochloride has been followed by 1H NMR spectroscopy. The same unfolding transition seen previously from circular dichroism studies at low denaturant concentration was detected here by discontinuous changes in the chemical shifts of the C(2) protons of two of the five histidines in human antithrombin III and of three of the six histidines in bovine antithrombin III. These two histidines in human antithrombin III are assigned to residue 1 and, more tentatively, to residue 65. Two of the three histidines similarly affected in the bovine protein appear to be homologous to residues in the human protein. This supports the proposal of similar structures for the two proteins. In the presence of heparin, the discontinuous titration behavior of these histidine resonances is shifted to higher denaturant concentration, reflecting the stabilization of the easily unfolded first domain of the protein by bound heparin. From the tentative assignment of one of these resonances to histidine-1, it is proposed that the heparin binding site of antithrombin III is located in the N-terminal region and that this region forms a separate domain from the rest of the protein. The pattern of disulfide linkages is such that this domain may well extend from residue 1 to at least residue 128. Thermal denaturation also leads to major perturbation of these two histidine resonances in human antithrombin III, though stable intermediates in the unfolding were not detected

  12. An Antithrombin-Heparin Complex Increases the Anticoagulant Activity of Fibrin Clots

    Directory of Open Access Journals (Sweden)

    Lesley J. Smith

    2008-01-01

    Full Text Available Clotting blood contains fibrin-bound thrombin, which is a major source of procoagulant activity leading to clot extension and further activation of coagulation. When bound to fibrin, thrombin is protected from inhibition by antithrombin (AT + heparin but is neutralized when AT and heparin are covalently linked (ATH. Here, we report the surprising observation that, rather than yielding an inert complex, thrombin-ATH formation converts clots into anticoagulant surfaces that effectively catalyze inhibition of thrombin in the surrounding environment.

  13. Anti-thrombin III, Protein C, and Protein S deficiency in acute coronary syndrome

    Directory of Open Access Journals (Sweden)

    Dasnan Ismail

    2002-06-01

    Full Text Available The final most common pathway for the majority of coronary artery disease is occlusion of a coronary vessel. Under normal conditions, antithrombin III (AT III, protein C, and protein S as an active protein C cofactor, are natural anticoagulants (hemostatic control that balances procoagulant activity (thrombin antithrombin complex balance to prevent thrombosis. If the condition becomes unbalanced, natural anticoagulants and the procoagulants can lead to thrombosis. Thirty subjects with acute coronary syndrome (ACS were studied for the incidence of antithrombin III (AT III, protein C, and protein S deficiencies, and the result were compare to the control group. Among patients with ACS, the frequency of distribution of AT-III with activity < 75% were 23,3% (7 of 30, and only 6,7% ( 2 of 30 in control subject. No one of the 30 control subject have protein C activity deficient, in ACS with activity < 70% were 13,3% (4 of 30. Fifteen out of the 30 (50% control subjects had protein S activity deficiency, while protein S deficiency activity < 70% was found 73.3.% (22 out of 30. On linear regression, the deterministic coefficient of AT-III activity deficiency to the development ACS was 13,25 %, and the deterministic coefficient of protein C activity deficient to the development of ACS was 9,06 %. The cut-off point for AT-III without protein S deficiency expected to contribute to the development of vessel disease was 45%. On discriminant analysis, protein C activity deficiency posed a risk for ACS of 4,5 greater than non deficient subjects, and AT-III activity deficiency posed a risk for ACS of 3,5 times greater than non deficient subjects. On binary logistic regression, protein S activity acted only as a reinforcing factor of AT-III activity deficiency in the development of ACS. Protein C and AT III deficiency can trigger ACS, with determinant coefficients of 9,06% and 13,25% respectively. Low levels of protein C posed a greater risk of

  14. Comparison of antithrombin activity of the polysulphate chitosan derivatives in in vivo and in vitro system.

    Science.gov (United States)

    Drozd, N N; Sher, A I; Makarov, V A; Galbraikh, L S; Vikhoreva, G A; Gorbachiova, I N

    2001-06-01

    In order to choose the proper method for evaluating the antithrombin activity in samples of chitosan polysulphate (CP) with different polymerization degrees and sulphation degrees, we estimated the ability of direct anticoagulants to depress the coagulability of recalcified sheep blood using the third international heparin standard (A1 - in vitro system) and determined such activity on pharmacodynamic curve (A2 - in vivo system). The curve admits the kinetics of CP elimination to be nonlinear in case of intravenous injection to rabbits, as it is observed in heparin: Ct = C(o)exp(-K(e)lt), where Ct is the CP concentration at the time moment t; C(o) is the CP concentration at the injection moment; Kel is the elimination constant. Besides, it is assumed that there is a linear approximation of the anticoagulant effect on the dose, which finally makes it possible to calculate the specific activity A2: T = KTCt+T(in), where T is the time of clot formation at different time intervals after CP injection; T(in) is the time of clot formation prior to CP injection. T value was assessed in two tests: blood coagulation time (BCT) and activated partial thromboplastin time (APTT). No correlation was observed between A1 and A2. At the same time, the values of Kel and the period of semi-elimination, with the use of the biospecific cetylpyridinium chloride electrophores for the quantitative determination of CP in rabbit's blood taken at different time intervals after injection, showed a close correlation (r = .94, P < .05) between the same parameters, obtained with the help of the rectilinear pharmacodynamic plot in BCT test. Thus, experimentally, it was proven that the assumption of the CP nonlinear elimination and the CP effect-dose dependence was true, which is necessary for A2 calculation. Relatively low molecular weights (MW 61-82 kDa, polymerization degree 188-252 ) and high sulphation patterns (sulphur amounts 15.6-16.9%, sulphation degree 1.58-1.86) were slowly cleared and

  15. Histidine-rich glycoprotein does not interfere with interactions between antithrombin III and heparin-like compounds on vascular endothelial cells

    International Nuclear Information System (INIS)

    The role of histidine-rich glycoprotein in controlling heparin-like compounds on the endothelial cell surface is still unclear. The effects of this heparin-neutralizing protein on the interaction between antithrombin III and cultured porcine aortic endothelial cells were examined. Displacement of 125I-labeled antithrombin III specifically bound to endothelial cells by unlabeled histidine-rich glycoprotein was much less potent than that by unlabeled antithrombin III. One hundred-fold molar excess of histidine-rich glycoprotein displaced specific 125I-antithrombin III binding only by 20%. Furthermore, the endothelial cell-mediated acceleration of thrombin inactivation by antithrombin III was diminished by protamine sulfate, but was not affected by histidine-rich glycoprotein even at a histidine-rich glycoprotein/antithrombin III molar ratio of approximately 7:1. These data indicate that histidine-rich glycoprotein does not interfere with the interaction of endothelial cell heparin-like compounds with antithrombin III. Thus, it may not play an important role in the modulation of anticoagulant activity of endothelial cells in vivo, suggesting that the commonly accepted view of the probable function of this protein is erroneous

  16. Dynamic properties of the native free antithrombin from molecular dynamics simulations: computational evidence for solvent- exposed Arg393 side chain.

    Science.gov (United States)

    Tóth, László; Fekete, Attila; Balogh, Gábor; Bereczky, Zsuzsanna; Komáromi, István

    2015-09-01

    While antithrombin (AT) has small basal inhibitory activity, it reaches its full inhibitory potential against activated blood coagulation factors, FXa, FIXa, and FIIa (thrombin), via an allosteric and/or template (bridging) mechanism by the action of heparin, heparan sulfate, or heparin-mimetic pentasaccharides (PS). From the numerous X-ray structures available for different conformational states of AT, only indirect and incomplete conclusions can be drawn on the inherently dynamic properties of AT. As a typical example, the basal inhibitory activity of AT cannot be interpreted on the basis of "non-activated" free antithrombin X-ray structures since the Arg393 side chain, playing crucial role in antithrombin-proteinase interaction, is not exposed. In order to reveal the intrinsic dynamic properties and the reason of basal inhibitory activity of antithrombin, 2 μs molecular dynamics simulations were carried out on its native free-forms. It was shown from the simulation trajectories that the reactive center loop which is functioning as "bait" for proteases, even without any biasing potential can populate conformational state in which the Arg393 side chain is solvent exposed. It is revealed from the trajectory analysis that the peptide sequences correspond to the helix D extension, and new helix P formation can be featured with especially large root-mean-square fluctuations. Mutual information analyses of the trajectory showed remarkable (generalized) correlation between those regions of antithrombin which changed their conformations as the consequence of AT-PS complex formation. This suggests that allosteric information propagation pathways are present even in the non-activated native form of AT. PMID:25483839

  17. Polyurethane films modified by antithrombin-heparin complex to enhance endothelialization: An original impedimetric analysis

    International Nuclear Information System (INIS)

    In this paper, polyurethane (PU) was deposited as a thin layer onto the surface of ITO (indium tin oxide) and was then modified with an antithrombin-heparin complex (ATH). The resulting films were characterized by ATR spectroscopy, contact angle measurements and electrochemical impedance spectroscopy (EIS). Physicochemical characterization confirmed the surface modifications. The obtained films were used as substrates for endothelial cell attachment and growth. These processes were characterized using electrochemical impedance spectroscopy (EIS). We observed that the addition of a small amount of heparin and AT additives onto the polymer surface resulted in a considerable change in the surface characteristics, and we found that PU films that were modified by the ATH complex were able to greatly enhance adhesion and proliferation of endothelial cells (ECs).

  18. Antithrombin attenuates myocardial dysfunction and reverses systemic fluid accumulation following burn and smoke inhalation injury: a randomized, controlled, experimental study

    OpenAIRE

    Rehberg, S; Yamamoto, Y; Bartha, E; Sousse, L.E. (Linda); Jonkam, C. (Collette); Zhu, Y; Traber, L.D. (Lillian); Cox, R. A.; Traber, D.L. (Daniel); Enkhbaatar, P

    2013-01-01

    Introduction: We hypothesized that maintaining physiological plasma levels of antithrombin attenuates myocardial dysfunction and inflammation as well as vascular leakage associated with burn and smoke inhalation injury. Therefore, the present prospective, randomized experiment was conducted using an established ovine model. Methods: Following 40% of total body surface area, third degree flame burn and 4 × 12 breaths of cold cotton smoke, chronically instrumented sheep were randomly assigned t...

  19. A recurrent deletion in the antithrombin gene, AT106-108(-6 bp), identified by DNA heteroduplex detection

    Energy Technology Data Exchange (ETDEWEB)

    Olds, R.J.; Thein, S.L. (John Radcliffe Hospital, Oxford (United Kingdom)); Lane, D.A. (Charing Cross and Westminster Medical School, London (United Kingdom)); Beresford, C.H.; Hughes, P.M. (Univ. of Otago Medical School, Dunedin (New Zealand)); Abildgaard, U. (Aker Hospital, Oslo (Norway))

    1993-04-01

    Antithrombin is the major physiological inhibitor of the activated serine proteinases of the coagulation system. Hereditary deficiency of the inhibitor is transmitted in an autosomal dominant pattern and is associated with a risk of venous thromboembotic disease in affected individuals. In the classical form of deficiency, type Ia, plasma antithrombin is reduced to approximately half normal in both functional and immunological assays. The authors report here the identification of a recurrent mutation as the basis for type Ia deficiency in two independent kindreds, one from New Zealand and the other from Norway, and demonstrate the utility of DNA heteroduplex detection as a method for screening for the presence of mutations. Standard functional and immunological assays for plasma antithrombin showed levels of approximately half normal in several members of both kindreds, consistent with the classification as type Ia deficiency. The plasma of the proband from the Norwegian kindred was examined by crossed immunoelectrophoresis, in the presence or absence of heparin in the first dimension, and an abnormal component that may have represented a variant form of the inhibitor was not identified. In both families affected members have had episodes of venous thrombosis, although some carriers of the abnormal allele, as confirmed in the current study, so far have not had clinical thrombotic disease. 7 refs., 2 figs.

  20. Fondaparinux bei Herz-Kreislauf-Erkrankungen: Ein neues Antithrombin mit herausragenden Eigenschaften

    Directory of Open Access Journals (Sweden)

    Huber K

    2008-01-01

    Full Text Available Fondaparinux, ein synthetisches Pentasaccharid, führt zu einer indirekten Hemmung des Gerinnungsfaktors Xa und behindert in der Folge die Bildung von Thrombin. Fondaparinux wurde als Vergleichssubstanz gegenüber unfraktioniertem (Standard- Heparin oder dem niedermolekularen Heparin Enoxaparin in der Prophylaxe oder Therapie von venösen Thrombosen getestet. Zuletzt wurde Fondaparinux auch bei Patienten mit akuten Koronarsyndromen (ACS untersucht: bei Patienten mit ACS ohne ST-Hebung (NSTE-ACS waren sowohl die Blutungsrate als auch die Kurz- und Langzeitmortalität im Fondaparinuxarm (2,5 mg/Tag s. c. signifikant geringer als in den Enoxaparin-behandelten Patienten (1 mg/kg KG 2×/Tag s. c. (OASIS-5-Studie. Bei Patienten mit akutem ST-Strecken-Hebungsinfarkt (STEMI war Fondaparinux in den Subgruppen der konservativ behandelten Patienten (ohne Reperfusion und der Patienten, die eine pharmakologische Reperfusion erhielten (Thrombolyse von Vorteil gegenüber Placebo oder unfraktioniertem Heparin. Hingegen zeigte sich bei Patienten mit STEMI, die einer Akut-PCI unterzogen wurden, eine starke Tendenz zugunsten von unfraktioniertem Heparin gegenüber Fondaparinux (OASIS-6-Studie. Daher wird Fondaparinux in den internationalen Richtlinien als das Antithrombin mit der günstigsten Risiko/Nutzen-Ratio bei NSTEMI aber auch bei STEMI-Patienten mit Ausnahme jener Patienten, die sich einer Akut-PCI unterziehen, empfohlen. Fondaparinux könnte schon in der nahen Zukunft die Heparine in diesen Indikationen weitgehend ersetzen.

  1. Comparative study of antithrombin III. Protease complex metabolism by fibroblasts and vascular endothelial cells

    International Nuclear Information System (INIS)

    125I-labeled human antithrombin III (125I-AT III).protease complexes are specifically bound to both cultured human skin fibroblast (HSF) cells and adult bovine aortic endothelial (ABAE) cells; however, there is a significant difference in the rate and degree of metabolism of the complexes by these two cell types. HSF cells appear to internalize the complexes at a rate of about 2.5 pmole/1 X 10(6) cells/h and subsequently degrade them at a rate of 0.6 pmole/1 X 10(6) cells/h. ABAE cells internalize and degrade the complexes at rates approximately 100 and 30 times lower, respectively. Neither cell type interacts with free 125I-AT III but only with its combined form with either thrombin or trypsin. These data indicate the major role of HSF cells in the removal of AT III.protease complexes from extravascular spaces in the body, in contrast to the inert vascular surface with regard to AT III.protease complexes provided by the vascular endothelium

  2. A capillary zone electrophoresis method to detect conformers and dimers of antithrombin in therapeutic preparations.

    Science.gov (United States)

    Marie, Anne-Lise; Tran, Nguyet Thuy; Saller, François; Abdou, Youmna Mohamed; Zeau, Pascal; Plantier, Jean-Luc; Urbain, Rémi; Borgel, Delphine; Taverna, Myriam

    2016-07-01

    Antithrombin (AT) is a human plasma glycoprotein that possesses anticoagulant and anti-inflammatory properties. However, the native (active) form of AT is unstable and undergoes conformational changes, leading to latent, cleaved, and heterodimeric forms. The presence of these alternative forms mostly inactive can highly impact the quality and therapeutic activity of pharmaceutical AT preparations. We developed a capillary zone electrophoresis method, based on a neutral polyethylene oxide-coated capillary and a buffer close to physiological conditions, enabling the separation of more than eight forms of AT. Several peaks were identified as native, latent, and heterodimeric forms. The CZE method was reproducible with intraday relative standard deviations less than 0.5 and 2% for migration times and peak areas, respectively. The method was applied to the comparison of AT preparations produced by five competitive pharmaceutical companies, and statistical tests were performed. Important differences in the proportion of each form were highlighted. In particular, one AT preparation was shown to contain a high quantity of heterodimer, and two preparations contained high quantities of latent form. In addition, one AT preparation exhibited additional forms, not yet identified. PMID:26989842

  3. Antithrombin reduces reperfusion-induced hepatic metastasis of colon cancer cells

    Institute of Scientific and Technical Information of China (English)

    Masanao Kurata; Kenji Okajima; Toru Kawamoto; Mitsuhiro Uchiba; Nobuhiro Ohkohchi

    2006-01-01

    AIM: To examine whether antithrombin (AT) could prevent hepatic ischemia/reperfusion (I/R)-induced hepatic metastasis by inhibiting tumor necrosis factor (TNF)-α-induced expression of E-selectin in rats.METHODS: Hepatic I/R was induced in rats and mice by clamping the left branches of the portal vein and the hepatic artery. Cancer cells were injected intrasplenically.The number of metastatic nodules was counted on day 7after I/R. TNF-α and E-selectin mRNA in hepatic tissue,serum fibrinogen degradation products and hepatic tissue levels of 6-keto-PGF1α, a stable metabolite of PGI2,were measured.RESULTS: AT inhibited increases in hepatic metastasis of tumor cells and hepatic tissue mRNA levels of TNF-αand E-selectin in animals subjected to hepatic I/R.Argatroban, a thrombin inhibitor, did not suppress any of these changes. Both AT and argatroban inhibited I/R-induced coagulation abnormalities. I/R-induced increases of hepatic tissue levels of 6-keto-PGF1αwere significantly enhanced by AT. Pretreatment with indomethacin completely reversed the effects of AT.Administration of OP-2507, a stable PGI2 analog, showed effects similar to those of AT in this model. Hepatic metastasis in congenit.al AT-deficient mice subjected to hepatic I/R was significantly increased compared to that observed in wild-type mice. Administration of AT significantly reduced the number of hepatic metastases in congenital AT-deficient mice.CONCLUSION: AT might reduce I/R-induced hepatic metastasis of colon cancer cells by inhibiting TNF-α-induced expression of E-selectin through an increase in the endothelial production of PGI2. These findings also raise the possibility that AT might prevent hepatic metastasis of tumor cells if administered during the resection of liver tumors.

  4. Biological Variations of Lupus Anticoagulant, Antithrombin, Protein C, Protein S, and von Willebrand Factor Assays.

    Science.gov (United States)

    Shou, Weiling; Chen, Qian; Wu, Wei; Cui, Wei

    2016-02-01

    The results of lupus anticoagulant (LA), antithrombin (AT), protein C (PC), and protein S (PS) testing, and the values of von Willebrand factor antigen (VWF:Ag) are important in diagnosis and therapeutic monitoring of thrombosis and hemostasis diseases. Till now, no published study has focused on the biological variations in LA testing, and only a few studies have examined the biological variations of AT, PC, PS, and VWF:Ag. With the latest fully automated instruments and improved reagents, the analytical, within-subject, and between-subject biological variations were estimated for these five coagulant parameters in a cohort of 25 apparently healthy subjects. Blood specimens were collected at 8:00 am, 12:00 pm, and 4:00 pm on days 1, 3, and 5. The analytical biological variation (CV(A)) values of all the parameters were less than 3%. The within-subject biological variation (CV(W)) and between-subject biological variation (CV(G)) values of the LA normalized ratio were 4.64 and 6.83%, respectively. No significant differences were observed in the intraday and interday biological variations of LA tests, or in AT, PC, PS, and VWF:Ag values. Additionally, the utility of the conventional population-based reference intervals of the five coagulation parameters was evaluated by the index of individuality, and data on CV(W) and CV(A) were used to calculate the reference change value to identify the significance of changes in serial results from the same individual. PMID:26516946

  5. Prevention and treatment of venous thromboembolism in pregnancy in patients with hereditary antithrombin deficiency

    Directory of Open Access Journals (Sweden)

    James AH

    2013-05-01

    Full Text Available Andra H James,1 Barbara A Konkle,2,3 Kenneth A Bauer4 1Department of Obstetrics and Gynecology, University of Virginia, Charlottesville, Virginia, 2Puget Sound Blood Center, Seattle, Washington, 3Department of Medicine, University of Washington, Seattle, Washington, 4Department of Medicine, Beth Israel Deaconess Medical Center and VA Boston Healthcare System, Harvard Medical School, Boston, Massachusetts, USA Objective: The aims of the study reported here were to provide data from six pregnant subjects who were enrolled in a clinical trial of antithrombin (AT concentrate, discuss other published case series and case reports, and provide general guidance for the use of AT concentrate for inherited AT deficiency in pregnancy. Methods: In the late 1980s, 31 AT-deficient subjects were enrolled in a prospective treatment trial of the plasma-derived AT concentrate Thrombate III®. Herein, newly available treatment data about the six pregnant subjects in the trial is tabulated and summarized. Results: All six experienced venous thromboembolism (VTE during pregnancy, were dosed according to a weight-based protocol, and were treated concomitantly with anticoagulation. Loading doses of AT concentrate of 54–62 units/kg were followed by maintenance doses of 50%–100% of the loading dose for 3–10 days. At the time of labor, loading doses of 46–50 units/kg were followed by maintenance doses of 50%–75% of the loading dose for 5–7 days. None of the six experienced recurrent thrombosis while receiving treatment with AT concentrate. Conclusion: Currently we suggest that women with AT deficiency who are pregnant or postpartum and have a personal history of VTE or current VTE receive AT concentrates. Keywords: thrombophilia, thrombosis, plasma-derived concentrate, labor, delivery, heparin.

  6. Interaction of antithrombin III with bovine aortic segments. Role of heparin in binding and enhanced anticoagulant activity.

    OpenAIRE

    Stern, D.; Nawroth, P; Marcum, J; Handley, D; Kisiel, W; Rosenberg, R; Stern, K.

    1985-01-01

    Bovine antithrombin III (AT III) interaction with the luminal surface of bovine aortic segments with a continuous layer of endothelium was examined. Incubation of 125I-AT III with vessel segments, previously washed free of endogenous AT III, demonstrated specific, time-dependent binding to the protease inhibitor to the endothelium. Half-maximal binding was observed at an added AT III concentration of 14 nM. Binding of 125I-AT III to the vessel wall was reversible (50% dissociated in 4 min), a...

  7. Resolution of preoperative portal vein thrombosis after administration of antithrombin III in living donor liver transplantation: case report.

    Science.gov (United States)

    Imai, H; Egawa, H; Kajiwara, M; Nakajima, A; Ogura, Y; Hatano, E; Ueda, M; Kawaguchi, Y; Kaido, T; Takada, Y; Uemoto, S

    2009-11-01

    A 59-year-old man with hepatitis C virus-associated liver cirrhosis was transferred to our hospital to undergo living donor liver transplantation. Coagulation was impaired (prothrombin time [International Normalized Ratio], 3.27), and antithrombin III (AT-III) activity was 23% (normal, 87%-115%). Contrast-enhanced computed tomography scans revealed portal vein thrombosis (PVT) from the junction between the splenic and superior mesenteric vein to the porta hepatica; the portal vein was completely obstructed (PVT). To prevent further development of PVT, 1500 U of AT-III was administered for 3 days, elevating the AT-III activity to 50%. A contrast-enhanced computed tomography scan obtained 9 days after AT-III administration showed resolution of PVT. Living donor liver transplantation was safely performed without portal vein grafting. Thus, a low AT-III concentration may have an important role in the pathogenesis of PVT in patients with cirrhosis. PMID:19917415

  8. Investigating changes in the gas-phase conformation of Antithrombin III upon binding of Arixtra using traveling wave ion mobility spectrometry (TWIMS)

    OpenAIRE

    Zhao, Yuejie; Singh, Arunima; Li, Lingyun; Linhardt, Robert J.; Xu, Yongmei; Liu, Jian; Woods, Robert J.; Amster, I. Jonathan

    2015-01-01

    We validate the utility of ion mobility to measure protein conformational changes induced by the binding of glycosaminoglycan ligands, using the well characterized system of Antithrombin III (ATIII) and Arixtra, a pharmaceutical agent with heparin (Hp) activity. Heparin has been used as a therapeutic anticoagulant drug for several decades through its interaction with ATIII, a serine protease inhibitor that plays a central role in the blood coagulation cascade. This interaction induces conform...

  9. Development of Methods for Measuring Protein C Inhibitor and Antithrombin: Use of Monoclonal Antibodies against the Reactive Center Loop-Inserted Forms of the Serpins

    OpenAIRE

    Kjellberg, Margareta

    2007-01-01

    Protein C inhibitor (PCI) and antithrombin (AT) are serine protease inhibitors (serpins) that are involved in the regulation of coagulation. Like other inhibitory serpins, PCI and AT adopt different structural conformations that are related to their functions. The cleaved, inactive form is a result of cleavage by a protease, and the latent form, which is also inactive, can arise due to a mutation in the serpin. Methods that quantify the different forms can be useful as diagnostic tools. The a...

  10. Purified radiolabeled antithrombin III metabolism in three families with hereditary AT III deficiency: application of a three-compartment model

    International Nuclear Information System (INIS)

    Purified human radioiodinated antithrombin III (125I-AT III) was used to study its metabolism in six members from three different families with a known hereditary AT III deficiency. Six healthy volunteers served as a control group. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and crossed immunoelectrophoresis (CIE) showed the purified AT III to be homogeneous. Amino acid analysis of the protein revealed a composition identical to a highly purified internal standard. The specific activity was 5.6 U/mg. Analysis of plasma radioactivity data was performed, using a three-compartment model. Neither plasma disappearance half-times nor fractional catabolic rate constants differed significantly between patients and control subjects. The mean absolute catabolic rate in the patient group was significantly lower than that of the control group at 2.57 +/- 0.44 and 4.46 +/- 0.80 mg/kg/day, respectively. In addition, the mean patient alpha 1-phase, flux ratio (k1,2 and k2,1) of the second compartment alpha 2-phase and influx (k3,1) of the third compartment were significantly reduced as compared with control values. It has been tentatively concluded that the observed reduction in the second compartment may be caused by a decrease in endothelial cell surface binding

  11. Localization of anticoagulantly active heparan sulfate proteoglycans in vascular endothelium: Antithrombin binding on cultured endothelial cells and perfused rat aorta

    International Nuclear Information System (INIS)

    We have studied the interaction of 125I-antithrombin (125I-AT) with microvascular endothelial cells (RFPEC) to localize the cellular site of anticoagulantly active heparan sulfate proteoglycans (HSPG). The radiolabeled protease inhibitor bound specifically to the above HSPG with a Kd of approximately 50 nM. Confluent monolayer RFPEC cultures exhibited a linear increase in the amount of AT bound per cell for up to 16 d, whereas suspension RFPEC cultures possessed a constant number of protease inhibitor binding sites per cell for up to 5 d. These results suggest that monolayer RFPEC cultures secrete anticoagulantly active HSPG, which then accumulate in the extracellular matrix. This hypothesis was confirmed by quantitative light and EM level autoradiography which demonstrated that the AT binding sites are predominantly located in the extracellular matrix with only small quantities of protease inhibitor complexed to the cell surface. We have also pinpointed the in vivo position of anticoagulantly active HSPG within the blood vessel wall. Rat aortas were perfused, in situ, with 125I-AT, and bound labeled protease inhibitor was localized by light and EM autoradiography. The anticoagulantly active HSPG were concentrated immediately beneath the aortic and vasa vasorum endothelium with only a very small extent of labeling noted on the luminal surface of the endothelial cells. Based upon the above data, we propose a model whereby luminal and abluminal anticoagulantly active HSPG regulate coagulation mechanism activity

  12. Circulating microparticles and the risk of thrombosis in inherited deficiencies of antithrombin, protein C and protein S.

    Science.gov (United States)

    Campello, Elena; Spiezia, Luca; Radu, Claudia M; Bulato, Cristiana; Gavasso, Sabrina; Tormene, Daniela; Woodhams, Barry; Dalla Valle, Fabio; Simioni, Paolo

    2016-01-01

    Many subjects carrying inherited thrombophilic defects will never experience venous thromboembolism (VTE) while other individuals developed recurrent VTE with no known additional risk factors. High levels of circulating microparticles (MP) have been associated with increased risk of VTE in patients with factor V Leiden and prothrombin G20210A mutation, suggesting a possible contribution of MP in the hypercoagulability of mild genetic thrombophilia. The role of MP as additional risk factor of VTE in carriers of natural clotting inhibitors defects (severe thrombophilia) has never been assessed. Plasma levels of annexin V-MP, endothelial-derived MP (EMP), platelet-derived MP (PMP), tissue factor-bearing MP (TF+) and the MP procoagulant activity (PPL) were measured in 132 carriers of natural anticoagulant deficiencies (25 antithrombin, 63 protein C and 64 protein S defect) and in 132 age and gender-matched healthy controls. Carriers of natural anticoagulant deficiencies, overall and separately considered, presented with higher median levels of annexin V-MP, EMP, PMP, TF+MP and PPL activity than healthy controls (pEMP and PMP had an adjusted OR for VTE of 3.36 (95% CI, 1.59 to 7.11), 9.26 (95% CI, 3.55 to 24.1) and 2.72 (95%CI, 1.16 to 6.38), respectively. Elevated levels of circulating MP can play a role in carriers of mild and severe inherited thrombophilia. The clinical implications of this association remain to be defined. PMID:26354831

  13. Impact of antithrombin Ⅲ on hepatic and intestinal microcirculation in experimental liver cirrhosis and bowel inflammation: An in vivo analysis

    Institute of Scientific and Technical Information of China (English)

    Sasa-Marcel Maksan; Zilfi (U)lger; Martha Maria Gebhard; Jan Schmidt

    2005-01-01

    AIM: To analyze the hepatic and intestinal microcirculation in an animal model of liver cirrhosis and inflammatory bowel disease (IBD) and to characterize the anti-inflammatory action of antithrombin Ⅲ (ATⅢ) on leukocyte kinetics and liver damage.METHODS: Hepatic and intestinal microcirculation was investigated by intravital videomicroscopy. Standardized models of experimental chronic liver cirrhosis and bowel inflammation were employed. Animals were divided into four groups (n = 6/group): controls, animals with cirrhosis,animals with cirrhosis and IBD, animals with cirrhosis and IBD treated with ATⅢ.RESULTS: Cirrhosis facilitated leukocyte rolling and sticking in hepatic sinusoids (1.91±0.28 sticker/μm vs0.5±0.5 sticker/μm in controls, P<0.05). The effect enhanced in animals with cirrhosis and IBD (5.4±1.65sticker/μm), but reversed agter ATⅢ application (3.97±1.04sticker/μm, P<0.05). Mucosal blood flow showed no differences in cirrhotic animals and controls (5.3±0.31nL/min vs5.4±0.25 nL/min) and was attenuated in animals with cirrhosis and IBD significantly (3.49±0.6 nL/min). This effect was normalized in the treatment group (5.13±0.4nL/min, P<0.05). Enzyme values rose during development of cirrhosis and bowel inflammation, and reduced after ATⅢ application (P<0.05).CONCLUSION: Liver cirrhosis in the presence of IBD leads to a significant reduction in mucosal blood flow and an increase in hepatic leukocyte adherence with consecutive liver injury, which can be prevented by administration of ATⅢ.

  14. Comparison of biological activities of human antithrombins with high-mannose or complex-type nonfucosylated N-linked oligosaccharides.

    Science.gov (United States)

    Yamada, Tsuyoshi; Kanda, Yutaka; Takayama, Makoto; Hashimoto, Akitoshi; Sugihara, Tsutomu; Satoh-Kubota, Ai; Suzuki-Takanami, Eri; Yano, Keiichi; Iida, Shigeru; Satoh, Mitsuo

    2016-05-01

    The structure of the N-linked oligosaccharides attached to antithrombin (AT) has been shown to affect its anticoagulant activity and pharmacokinetics. Human AT has biantennary complex-type oligosaccharides with the unique feature of lacking a core fucose, which affects its biological activities by changing its heparin-binding affinity. In human plasma, AT circulates as a mixture of the α-form bearing four oligosaccharides and the β-form lacking an oligosaccharide at Asn135. However, it remains unclear how the immature high-mannose-type oligosaccharides produced by mammalian cells affect biological activities of AT. Here, we succeeded in directly comparing the activities between the high-mannose and complex types. Interestingly, although there were no substantial differences in thrombin inhibitory activity, the high-mannose type showed higher heparin-binding affinity. The anticoagulant activities were increased by heparin and correlated with the heparin-binding affinity, resulting in the strongest anticoagulant activity being displayed in the β-form with the high-mannose type. In pharmacokinetic profiling, the high-mannose type showed a much shorter plasma half-life than the complex type. The β-form was found to have a prolonged plasma half-life compared with the α-form for the high-mannose type; conversely, the α-form showed a longer half-life than the β-form for the complex-type. The present study highlights that AT physiological activities are strictly controlled not only by a core fucose at the reducing end but also by the high-mannose-type structures at the nonreducing end. The β-form with the immature high-mannose type appears to function as a more potent anticoagulant than the AT typically found in human plasma, once it emerges in the blood. PMID:26747427

  15. Recombinant Technology and Probiotics

    Directory of Open Access Journals (Sweden)

    Icy D’Silva

    2011-09-01

    Full Text Available Recombinant technology has led the way to monumental advances in the development of useful molecules, including the development of safe probiotics. The development of novel approaches using recombinant technology and probiotics that allow accurate targeting of therapeutics to the mucosa is an interesting area of research. The creation and use of recombinant probiotics expressing recombinantovalbumin, recombinant ovalbumin mutants and yet-to-be-designed recombinant hypo/non-allergenic molecules offer the opportunity to further investigate their effects for food, nutrition, environment andhealth. This review highlights advances in native probiotics and recombinant probiotics expressing native and recombinant molecules for food, nutrition, environment and health.

  16. A prospective cohort study on the absolute risks of venous thromboembolism and predictive value of screening asymptomatic relatives of patients with hereditary deficiencies of protein S, protein C or antithrombin.

    NARCIS (Netherlands)

    Mahmoodi, B.K.; Brouwer, J.L.P.; Kate, M.K. Ten; Lijfering, W.M.; Veeger, N.J.; Mulder, A.B.; Kluin-Nelemans, H.C.; Meer, J. van der

    2010-01-01

    BACKGROUND: Absolute risks of venous thromboembolism (VTE) in protein S-, protein C-, or antithrombin-deficient subjects are mainly based on retrospective data. Screening asymptomatic relatives of these patients is disputed, though studies addressing this issue have yet to be conducted. METHODS: We

  17. Recombinant DNA in Medicine

    OpenAIRE

    Cederbaum, Stephen D.; Fareed, George C.; Lovett, Michael A.; Shapiro, Larry J.

    1984-01-01

    Studies in bacteria and bacterial viruses have led to methods to manipulate and recombine DNA in unique and reproducible ways and to amplify these recombined molecules millions of times. Once properly identified, the recombinant DNA molecules can be used in various ways useful in medicine and human biology. There are many applications for recombinant DNA technology. Cloned complementary DNA has been used to produce various human proteins in microorganisms. Insulin and growth hormone have been...

  18. Improving baculovirus recombination

    OpenAIRE

    Zhao, Yuguang; Chapman, David A. G.; Jones, Ian M.

    2003-01-01

    Recombinant baculoviruses have established themselves as a favoured technology for the high-level expression of recombinant proteins. The construction of recombinant viruses, however, is a time consuming step that restricts consideration of the technology for high throughput developments. Here we use a targeted gene knockout technology to inactivate an essential viral gene that lies adjacent to the locus used for recombination. Viral DNA prepared from the knockout fails to initiate an infecti...

  19. Therapeutic Recombinant Monoclonal Antibodies

    Science.gov (United States)

    Bakhtiar, Ray

    2012-01-01

    During the last two decades, the rapid growth of biotechnology-derived techniques has led to a myriad of therapeutic recombinant monoclonal antibodies with significant clinical benefits. Recombinant monoclonal antibodies can be obtained from a number of natural sources such as animal cell cultures using recombinant DNA engineering. In contrast to…

  20. Photoionization and Recombination

    Science.gov (United States)

    Nahar, Sultana N.

    2000-01-01

    Theoretically self-consistent calculations for photoionization and (e + ion) recombination are described. The same eigenfunction expansion for the ion is employed in coupled channel calculations for both processes, thus ensuring consistency between cross sections and rates. The theoretical treatment of (e + ion) recombination subsumes both the non-resonant recombination ("radiative recombination"), and the resonant recombination ("di-electronic recombination") processes in a unified scheme. In addition to the total, unified recombination rates, level-specific recombination rates and photoionization cross sections are obtained for a large number of atomic levels. Both relativistic Breit-Pauli, and non-relativistic LS coupling, calculations are carried out in the close coupling approximation using the R-matrix method. Although the calculations are computationally intensive, they yield nearly all photoionization and recombination parameters needed for astrophysical photoionization models with higher precision than hitherto possible, estimated at about 10-20% from comparison with experimentally available data (including experimentally derived DR rates). Results are electronically available for over 40 atoms and ions. Photoionization and recombination of He-, and Li-like C and Fe are described for X-ray modeling. The unified method yields total and complete (e+ion) recombination rate coefficients, that can not otherwise be obtained theoretically or experimentally.

  1. Recombineering Homologous Recombination Constructs in Drosophila

    OpenAIRE

    Carreira-Rosario, Arnaldo; Scoggin, Shane; Shalaby, Nevine A.; Williams, Nathan David; Hiesinger, P. Robin; Buszczak, Michael

    2013-01-01

    The continued development of techniques for fast, large-scale manipulation of endogenous gene loci will broaden the use of Drosophila melanogaster as a genetic model organism for human-disease related research. Recent years have seen technical advancements like homologous recombination and recombineering. However, generating unequivocal null mutations or tagging endogenous proteins remains a substantial effort for most genes. Here, we describe and demonstrate techniques for using recombineeri...

  2. An antithrombin-dependent sulfated polysaccharide isolated from the green alga Caulerpa cupressoides has in vivo anti- and prothrombotic effects Um polissacarídeo sulfatado dependente de antitrombina isolado da alga verde Caulerpa cupressoides possui efeitos anti- e pró-trombótico in vivo

    OpenAIRE

    José Ariévilo Gurgel Rodrigues; Ismael Nilo Lino de Queiroz; Ana Luíza Gomes Quinderé; Bruno Cunha Vairo; Paulo Antônio de Souza Mourão; Norma Maria Barros Benevides

    2011-01-01

    Red algae sulfated polysaccharides (SPs) have been widely described as anticoagulant and antithrombotic agents; however no description of antithrombotic activity regarding green algae SPs has been reported. Caulerpa cupressoides (Chlorophyta) has three different SPs fractions (SP1, SP2 and SP3). We investigated the effects of SP2 on thrombin activity by antithrombin and in an experimental model of venous thrombosis in rats. The inhibition of thrombin assay was evaluated using antithrombin (AT...

  3. Fundamental study of recombination and recombineering in Escherichia coli

    OpenAIRE

    Sun, Xiaohang; Huang, Yang

    2008-01-01

    Recombination and recombineering systems have been used in Escherichia coli to recombinant DNA sequences. With endonuclease and DNA lipase the bacterial plasmid and target DNA fragment can bind together and recombinant for a new DNA sequences. Red Proteins have been used in recombineering system to perform the function as the enzymes in recombination system, and faster and easier than the other way of recombinant new DNA sequences in E.coli. In this report we get to know the pr...

  4. Human recombinant interleukin-1 beta- and tumor necrosis factor alpha-mediated suppression of heparin-like compounds on cultured porcine aortic endothelial cells

    International Nuclear Information System (INIS)

    Cytokines are known to tip the balance of the coagulant-anticoagulant molecules on the endothelial cell surface toward intravascular coagulation. Their effects on endothelial cell surface-associated heparin-like compounds have not been examined yet. Incorporation of [35S]sulfate into heparan sulfate on cultured porcine aortic endothelial cells was suppressed by human recombinant interleukin-1 beta (rIL-1 beta) or tumor necrosis factor alpha (rTNF alpha) in a dose- and time-dependent manner with little effect on cell number, protein content, and [3H]leucine incorporation of cells. Maximal inhibition was achieved by incubation of cells with 100 ng/ml of rIL-1 beta or 5 ng/ml of rTNF alpha for 12-24 hours, resulting in a reduction of the synthesis of heparan sulfate on the cell surface by approximately 50%. The dose dependency was consistent with that seen in the stimulation of endothelial cell procoagulant activity by each cytokine. The suppression of heparan sulfate synthesis was sustained for at least 48 hours after pretreatment of cells with cytokines and was unchanged after the addition of indomethacin or polymyxin B. The rate of degradation of prelabeled 35S-heparan sulfate on the cell surface was not altered by cytokine treatments. Neither the size, the net negative charge, nor the proportion of the molecule with high affinity for antithrombin III of endothelial cell heparan sulfate was changed by cytokines. Furthermore, specific binding of 125I-labeled antithrombin III to the endothelial cell surface was reduced to 40-60% of control by cytokines. In parallel with reduction in binding, antithrombin III cofactor activity was partially diminished in cytokine-treated endothelial cells. Thus, cytokine-mediated suppression of heparin-like substance on endothelial cells appears to be another cytokine-inducible endothelial effects affecting coagulation

  5. Expression of Recombinant Antibodies

    OpenAIRE

    Frenzel, André; Hust, Michael; Schirrmann, Thomas

    2013-01-01

    Recombinant antibodies are highly specific detection probes in research, diagnostics, and have emerged over the last two decades as the fastest growing class of therapeutic proteins. Antibody generation has been dramatically accelerated by in vitro selection systems, particularly phage display. An increasing variety of recombinant production systems have been developed, ranging from Gram-negative and positive bacteria, yeasts and filamentous fungi, insect cell lines, mammalian cells to transg...

  6. PEGylation of Hirudin and Analysis of Its Antithrombin Activity in vitro%水蛭素聚乙二醇化及其体外抗凝活力分析

    Institute of Scientific and Technical Information of China (English)

    秦海娜; 修志龙; 张代佳; 包永明; 李晓晖; 韩国柱

    2007-01-01

    Hirudin is the most anticoagulant drug found in nature, but its short serum half-life significantly inhibits its clinical application. The PEGylation of hirudin, the most promising anticoagulant drug, was performed in this paper. The optimal reaction conditions for PEGylated hirudin were investigated. When the PEGylation reaction was conducted under 4℃ after 10h, in the borate buffer at pH 8.5, with the molar ratio 250: 1 of PEG to hirudin, a higher modification extent was achieved. Finally, the bioactivity of PEGylated hirudin was measured in vitro.Compared with unmodified hirudin, 26% of anti-thrombin activity was retained.

  7. Regulation of Meiotic Recombination

    Energy Technology Data Exchange (ETDEWEB)

    Gregory p. Copenhaver

    2011-11-09

    Meiotic recombination results in the heritable rearrangement of DNA, primarily through reciprocal exchange between homologous chromosome or gene conversion. In plants these events are critical for ensuring proper chromosome segregation, facilitating DNA repair and providing a basis for genetic diversity. Understanding this fundamental biological mechanism will directly facilitate trait mapping, conventional plant breeding, and development of genetic engineering techniques that will help support the responsible production and conversion of renewable resources for fuels, chemicals, and the conservation of energy (1-3). Substantial progress has been made in understanding the basal recombination machinery, much of which is conserved in organisms as diverse as yeast, plants and mammals (4, 5). Significantly less is known about the factors that regulate how often and where that basal machinery acts on higher eukaryotic chromosomes. One important mechanism for regulating the frequency and distribution of meiotic recombination is crossover interference - or the ability of one recombination event to influence nearby events. The MUS81 gene is thought to play an important role in regulating the influence of interference on crossing over. The immediate goals of this project are to use reverse genetics to identify mutants in two putative MUS81 homologs in the model plant Arabidopsis thaliana, characterize those mutants and initiate a novel forward genetic screen for additional regulators of meiotic recombination. The long-term goal of the project is to understand how meiotic recombination is regulated in higher eukaryotes with an emphasis on the molecular basis of crossover interference. The ability to monitor recombination in all four meiotic products (tetrad analysis) has been a powerful tool in the arsenal of yeast geneticists. Previously, the qrt mutant of Arabidopsis, which causes the four pollen products of male meiosis to remain attached, was developed as a facile system

  8. Recombination in ionized gases

    International Nuclear Information System (INIS)

    In this paper it is shown how capture-stabilized methodology (both macroscopic and microscopic) can provide a generic basis for a unified treatment of all of the above recombination mechanisms. A new semiclassical theory of dissociative recombination is also presented in an effort to gain further insight into the physics not included in the first-order treatment and difficult to extract from numerical quantal treatments based on configuration mixing and on multichannel quantum defect theory. A simple analytical expression more accurate than the standard first-order result is obtained for the cross section σ and rate coefficient α. (author)

  9. Investigating changes in the gas-phase conformation of Antithrombin III upon binding of Arixtra using traveling wave ion mobility spectrometry (TWIMS).

    Science.gov (United States)

    Zhao, Yuejie; Singh, Arunima; Li, Lingyun; Linhardt, Robert J; Xu, Yongmei; Liu, Jian; Woods, Robert J; Amster, I Jonathan

    2015-10-21

    We validate the utility of ion mobility to measure protein conformational changes induced by the binding of glycosaminoglycan ligands, using the well characterized system of Antithrombin III (ATIII) and Arixtra, a pharmaceutical agent with heparin (Hp) activity. Heparin has been used as a therapeutic anticoagulant drug for several decades through its interaction with ATIII, a serine protease inhibitor that plays a central role in the blood coagulation cascade. This interaction induces conformational changes within ATIII that dramatically enhance the ATIII-mediated inhibition rate. Arixtra is the smallest synthetic Hp containing the specific pentasaccharide sequence required to bind with ATIII. Here we report the first travelling wave ion mobility mass spectrometry (TWIMS) investigation of the conformational changes in ATIII induced by its interaction with Arixtra. Native electrospray ionization mass spectrometry allowed the gentle transfer of the native topology of ATIII and ATIII-Arixtra complex. IM measurements of ATIII and ATIII-Arixtra complex showed a single structure, with well-defined collisional cross section (CCS) values. An average 3.6% increase in CCS of ATIII occurred as a result of its interaction with Arixtra, which agrees closely with the theoretical estimation of the change in CCS based on protein crystal structures. A comparison of the binding behavior of ATIII under both denaturing and non-denaturing conditions confirmed the significance of a folded tertiary structure of ATIII for its biological activity. A Hp oligosaccharide whose structure is similar to Arixtra but missing the 3-O sulfo group on the central glucosamine residue showed a dramatic decrease in binding affinity towards ATIII, but no change in the mobility behavior of the complex, consistent with prior studies that suggested that 3-O sulfation affects the equilibrium constant for binding to ATIII, but not the mode of interaction. In contrast, nonspecific binding by a Hp

  10. Recombinant DNA for Teachers.

    Science.gov (United States)

    Duvall, James G., III

    1992-01-01

    A science teacher describes his experience at a workshop to learn to teach the Cold Spring Harbor DNA Science Laboratory Protocols. These protocols lead students through processes for taking E. coli cells and transforming them into a new antibiotic resistant strain. The workshop featured discussions of the role of DNA recombinant technology in…

  11. Recombineering Pseudomonas syringae

    Science.gov (United States)

    Here we report the identification of functions that promote genomic recombination of linear DNA introduced into Pseudomonas cells by electroporation. The genes encoding these functions were identified in Pseudomonas syringae pv. syringae B728a based on similarity to the lambda Red Exo/Beta and RecE...

  12. Characterization of IXINITY® (Trenonacog Alfa), a Recombinant Factor IX with Primary Sequence Corresponding to the Threonine-148 Polymorph.

    Science.gov (United States)

    Monroe, Dougald M; Jenny, Richard J; Van Cott, Kevin E; Buhay, Shelly; Saward, Laura L

    2016-01-01

    The goal of these studies was to extensively characterize the first recombinant FIX therapeutic corresponding to the threonine-148 (Thr-148) polymorph, IXINITY (trenonacog alfa [coagulation factor IX (recombinant)]). Gel electrophoresis, circular dichroism, and gel filtration were used to determine purity and confirm structure. Chromatographic and mass spectrometry techniques were used to identify and quantify posttranslational modifications. Activity was assessed as the ability to activate factor X (FX) both with and without factor VIIIa (FVIIIa) and in a standard clotting assay. All results were consistent across multiple lots. Trenonacog alfa migrated as a single band on Coomassie-stained gels; activity assays were normal and showed factor IX (FIXa) per IU of FIX. The molecule has >97%  γ-carboxylation and underwent the appropriate structural change upon binding calcium ions. Trenonacog alfa was activated normally with factor XIa (FXIa); once activated it bound to FVIIIa and FXa. When activated to FIXa, it was inhibited efficiently by antithrombin. Glycosylation patterns were similar to plasma-derived FIX with sialic acid content consistent with the literature reports of good pharmacokinetic performance. These studies have shown that trenonacog alfa is a highly pure product with a primary sequence and posttranslational modifications consistent with the common Thr-148 polymorphism of plasma-derived FIX. PMID:26997955

  13. Characterization of IXINITY® (Trenonacog Alfa, a Recombinant Factor IX with Primary Sequence Corresponding to the Threonine-148 Polymorph

    Directory of Open Access Journals (Sweden)

    Dougald M. Monroe

    2016-01-01

    Full Text Available The goal of these studies was to extensively characterize the first recombinant FIX therapeutic corresponding to the threonine-148 (Thr-148 polymorph, IXINITY (trenonacog alfa [coagulation factor IX (recombinant]. Gel electrophoresis, circular dichroism, and gel filtration were used to determine purity and confirm structure. Chromatographic and mass spectrometry techniques were used to identify and quantify posttranslational modifications. Activity was assessed as the ability to activate factor X (FX both with and without factor VIIIa (FVIIIa and in a standard clotting assay. All results were consistent across multiple lots. Trenonacog alfa migrated as a single band on Coomassie-stained gels; activity assays were normal and showed 97%  γ-carboxylation and underwent the appropriate structural change upon binding calcium ions. Trenonacog alfa was activated normally with factor XIa (FXIa; once activated it bound to FVIIIa and FXa. When activated to FIXa, it was inhibited efficiently by antithrombin. Glycosylation patterns were similar to plasma-derived FIX with sialic acid content consistent with the literature reports of good pharmacokinetic performance. These studies have shown that trenonacog alfa is a highly pure product with a primary sequence and posttranslational modifications consistent with the common Thr-148 polymorphism of plasma-derived FIX.

  14. Recombinant influenza vaccines.

    Science.gov (United States)

    Sedova, E S; Shcherbinin, D N; Migunov, A I; Smirnov, Iu A; Logunov, D Iu; Shmarov, M M; Tsybalova, L M; Naroditskiĭ, B S; Kiselev, O I; Gintsburg, A L

    2012-10-01

    This review covers the problems encountered in the construction and production of new recombinant influenza vaccines. New approaches to the development of influenza vaccines are investigated; they include reverse genetics methods, production of virus-like particles, and DNA- and viral vector-based vaccines. Such approaches as the delivery of foreign genes by DNA- and viral vector-based vaccines can preserve the native structure of antigens. Adenoviral vectors are a promising gene-delivery platform for a variety of genetic vaccines. Adenoviruses can efficiently penetrate the human organism through mucosal epithelium, thus providing long-term antigen persistence and induction of the innate immune response. This review provides an overview of the practicability of the production of new recombinant influenza cross-protective vaccines on the basis of adenoviral vectors expressing hemagglutinin genes of different influenza strains. PMID:23346377

  15. RECOMBINANT INFLUENZA VACCINES

    OpenAIRE

    Sedova, E.; Shcherbinin, D.; Migunov, A.; Smirnov, Iu; Logunov, D.; Shmarov, M.; Tsybalova, L.; Naroditskiĭ, B.; O. Kiselev; Gintsburg, A.

    2012-01-01

    This review covers the problems encountered in the construction and production of new recombinant influenza vaccines. New approaches to the development of influenza vaccines are investigated; they include reverse genetics methods, production of virus-like particles, and DNA- and viral vector-based vaccines. Such approaches as the delivery of foreign genes by DNA- and viral vector-based vaccines can preserve the native structure of antigens. Adenoviral vectors are a promising gene-delivery pla...

  16. Soluble recombinant influenza vaccines.

    OpenAIRE

    Fiers, W; Neirynck, S; Deroo, T; Saelens, X; Jou, W M

    2001-01-01

    Soluble, recombinant forms of influenza A virus haemagglutinin and neuraminidase have been produced in cells of lower eukaryotes, and shown in a mouse model to induce complete protective immunity against a lethal virus challenge. Soluble neuraminidase, produced in a baculovirus system, consisted of tetramers, dimers and monomers. Only the tetramers were enzymatically active. The immunogenicity decreased very considerably in the order tetra > di > mono. Therefore, we fused the head part of the...

  17. Nonradiative recombination in semiconductors

    CERN Document Server

    Abakumov, VN; Yassievich, IN

    1991-01-01

    In recent years, great progress has been made in the understandingof recombination processes controlling the number of excessfree carriers in semiconductors under nonequilibrium conditions. As a result, it is now possible to give a comprehensivetheoretical description of these processes. The authors haveselected a number of experimental results which elucidate theunderlying physical problems and enable a test of theoreticalmodels. The following topics are dealt with: phenomenological theory ofrecombination, theoretical models of shallow and deep localizedstates, cascade model of carrier captu

  18. Recombinant Collagenlike Proteins

    Science.gov (United States)

    Fertala, Andzej

    2007-01-01

    A group of collagenlike recombinant proteins containing high densities of biologically active sites has been invented. The method used to express these proteins is similar to a method of expressing recombinant procollagens and collagens described in U. S. Patent 5,593,859, "Synthesis of human procollagens and collagens in recombinant DNA systems." Customized collagenous proteins are needed for biomedical applications. In particular, fibrillar collagens are attractive for production of matrices needed for tissue engineering and drug delivery. Prior to this invention, there was no way of producing customized collagenous proteins for these and other applications. Heretofore, collagenous proteins have been produced by use of such biological systems as yeasts, bacteria, and transgenic animals and plants. These products are normal collagens that can also be extracted from such sources as tendons, bones, and hides. These products cannot be made to consist only of biologically active, specific amino acid sequences that may be needed for specific applications. Prior to this invention, it had been established that fibrillar collagens consist of domains that are responsible for such processes as interaction with cells, binding of growth factors, and interaction with a number of structural proteins present in the extracellular matrix. A normal collagen consists of a sequence of domains that can be represented by a corresponding sequence of labels, e.g., D1D2D3D4. A collagenlike protein of the present invention contains regions of collagen II that contain multiples of a single domain (e.g., D1D1D1D1 or D4D4D4D4) chosen for its specific biological activity. By virtue of the multiplicity of the chosen domain, the density of sites having that specific biological activity is greater than it is in a normal collagen. A collagenlike protein according to this invention can thus be made to have properties that are necessary for tissue engineering.

  19. Primordial magnetogenesis before recombination

    CERN Document Server

    Fabre, Ophélia

    2015-01-01

    The origin of large magnetic fields in the Universe remains currently unknown. We investigate here a mechanism before recombination based on known physics. The source of the vorticity is due to the changes in the photon distribution function caused by the fluctuations in the background photons. We show that the magnetic field generated in the MHD limit, due to the Coulomb scattering, is of the order $10^{-49}$ G. We explicitly show that the magnetic fields generated from this process are sustainable and are not erased by resistive diffusion. We compare the results with current observations and discuss the implications.

  20. CRMAGE: CRISPR Optimized MAGE Recombineering

    OpenAIRE

    Carlotta Ronda; Lasse Ebdrup Pedersen; Sommer, Morten O. A.; Alex Toftgaard Nielsen

    2016-01-01

    A bottleneck in metabolic engineering and systems biology approaches is the lack of efficient genome engineering technologies. Here, we combine CRISPR/Cas9 and λ Red recombineering based MAGE technology (CRMAGE) to create a highly efficient and fast method for genome engineering of Escherichia coli. Using CRMAGE, the recombineering efficiency was between 96.5% and 99.7% for gene recoding of three genomic targets, compared to between 0.68% and 5.4% using traditional recombineering. For modulat...

  1. Cell biology of mitotic recombination

    DEFF Research Database (Denmark)

    Lisby, Michael; Rothstein, Rodney

    2015-01-01

    Homologous recombination provides high-fidelity DNA repair throughout all domains of life. Live cell fluorescence microscopy offers the opportunity to image individual recombination events in real time providing insight into the in vivo biochemistry of the involved proteins and DNA molecules as w...

  2. Correlative Analysis of the Relationships and Differences on D-dimer, Fibrinogen and Antithrombin Ⅲ Between Varied Clinical Periods of Cerebral Infarction%D-D、Fb和AT-Ⅲ在脑梗死不同时期的变化及相关性分析

    Institute of Scientific and Technical Information of China (English)

    徐威香; 武蓉珍; 胡晓蕾

    2012-01-01

    目的:探讨血浆D-二聚体(D-D)、纤维蛋白原(Fb)和抗凝血酶Ⅲ(AT-Ⅲ)在脑梗死(CI)不同时期的变化及其临床意义.方法:根据临床特征,对260例CI患者进行分组,其中CI急性期组80例、进展期组41例、非进展期组65例、康复期组74例;90例体检健康者为正常对照组.采用SYSMEX CA7000血凝仪分别检测其血浆D-D、Fb和AT-Ⅲ水平.结果:CI急性期、进展期、非进展期患者D-D、Fb含量均明显高于正常对照组(P<0.01),AT-Ⅲ低于正常对照组(P<0.01);脑梗死组中,D-D与AT-Ⅲ呈负相关(P<0.01),D-D与Fb呈正相关(P<0.01),AT-Ⅲ与Fb无相关性.结论:CI患者D-D、Fb、AT-Ⅲ变化显著,D-D升高伴随AT-Ⅲ含量降低,提示D-D、Fb、AT-Ⅲ共同参与了梗死发生发展的病理生理过程,可作为CI临床危险分级和病情监测的指标.%Objective To investigate the differences and its clinical significance of D-dimer, fibrinogen and antithrombin Ⅲ between varied clinical periods of cerebral infarction( CI). Methods 328 CI patients were rolled into the study, and they were divided into four groups due to their different clinical periods as follows: group acute period (80) , group progressing(41) , group non-pro-gressing(65) , group convalescence(74). And, 90 healthy volunteers were rolled into the normal control group. Their plasma D-dimer, fibrinogen and antithrombin HI were detected on SYSMEX CA7000 automatic coagulation analyzer. Results D-dimer and fibrinogen of CI patients in the acute, progressing and non-progressing periods were significantly higher (P <0.01) than those of healthy volunteers, while antithrombin Ⅲ of them was significantly lower (P<0.01) than that of healthy volunteers. In CI patients, D-dimer correlated negatively with antithrombin Ⅲ, while positively with fibrinogen. No significant relationship was observed between antithrombin Ⅲ and fibrinogen. ConclUSin D-dimer, fibrinogen and antithrombin Ⅲ of CI patients varied significantly

  3. Delayed recombination and standard rulers

    International Nuclear Information System (INIS)

    Measurements of baryonic acoustic oscillations (BAOs) in galaxy surveys have been recognized as a powerful tool for constraining dark energy. However, this method relies on the knowledge of the size of the acoustic horizon at recombination derived from cosmic microwave background (CMB) anisotropy measurements. This estimate is typically derived assuming a standard recombination scheme; additional radiation sources can delay recombination altering the cosmic ionization history and the cosmological inferences drawn from CMB and BAO data. In this paper we quantify the effect of delayed recombination on the determination of dark energy parameters from future BAO surveys such as the Baryon Oscillation Spectroscopic Survey and the Wide-Field Multi-Object Spectrograph. We find the impact to be small but still not negligible. In particular, if recombination is nonstandard (to a level still allowed by CMB data), but this is ignored, future surveys may incorrectly suggest the presence of a redshift-dependent dark energy component. On the other hand, in the case of delayed recombination, adding to the analysis one extra parameter describing deviations from standard recombination does not significantly degrade the error bars on dark energy parameters and yields unbiased estimates. This is due to the CMB-BAO complementarity.

  4. Hemothorax under thrombolytic therapy with recombinant tissue: plasminogen activator (rt-PA) in a 16-year-old girl.

    Science.gov (United States)

    Varnholt, V; Ringe, H; Nietsch, L; Gaedicke, G

    1999-12-01

    We present the case of a 16-year-old girl with an extended thrombosis of the femoral and iliac vein and the inferior vena cava during pleuropneumonia; predisposing risk factors for thrombophilia were: use of contraceptives, nicotine abuse and congenital deficiency of antithrombin III (not previously diagnosed). Thrombolytic therapy with recombinant tissue plasminogen activator (rt-PA; initial dose: 0.08 mg/kg/h) was started. 2 days later--after diagnosis of an extended hemothorax: 1500 ml blood were obtained after thoracocentesis, transfusion of packed red blood cells was necessary--rt-PA was stopped, with only heparin (400 U/kg/d) being administered. 36 h later--the thrombosis had not yet changed--the thrombolytic therapy with rt-PA was continued in a markedly reduced dose (0.015 mg/kg/d) with no further bleeding complications. 8 days later--after successful thrombolysis--t-PA was stopped, heparin was given for another 10 days, then cumarin was administered orally. PMID:10650854

  5. Cell encoding recombinant human erythropoietin

    Energy Technology Data Exchange (ETDEWEB)

    Beck, A.K.; Withy, R.M.; Zabrecky, J.R.; Masiello, N.C.

    1990-09-04

    This patent describes a C127 cell transformed with a recombinant DNA vector. It comprises: a DNA sequence encoding human erythropoietin, the transformed cell being capable of producing N-linked and O-linked glycosylated human erythropoietin.

  6. Three Decades of Recombinant DNA.

    Science.gov (United States)

    Palmer, Jackie

    1985-01-01

    Discusses highlights in the development of genetic engineering, examining techniques with recombinant DNA, legal and ethical issues, GenBank (a national database of nucleic acid sequences), and other topics. (JN)

  7. Stable recombination hotspots in birds.

    Science.gov (United States)

    Singhal, Sonal; Leffler, Ellen M; Sannareddy, Keerthi; Turner, Isaac; Venn, Oliver; Hooper, Daniel M; Strand, Alva I; Li, Qiye; Raney, Brian; Balakrishnan, Christopher N; Griffith, Simon C; McVean, Gil; Przeworski, Molly

    2015-11-20

    The DNA-binding protein PRDM9 has a critical role in specifying meiotic recombination hotspots in mice and apes, but it appears to be absent from other vertebrate species, including birds. To study the evolution and determinants of recombination in species lacking the gene that encodes PRDM9, we inferred fine-scale genetic maps from population resequencing data for two bird species: the zebra finch, Taeniopygia guttata, and the long-tailed finch, Poephila acuticauda. We found that both species have recombination hotspots, which are enriched near functional genomic elements. Unlike in mice and apes, most hotspots are shared between the two species, and their conservation seems to extend over tens of millions of years. These observations suggest that in the absence of PRDM9, recombination targets functional features that both enable access to the genome and constrain its evolution. PMID:26586757

  8. Combinatorics in Recombinational Population Genomics

    Science.gov (United States)

    Parida, Laxmi

    The work that I will discuss is motivated by the need for understanding, and processing, the manifestations of recombination events in chromosome sequences. In this talk, we focus on two related problems. First, we explore the very general problem of reconstructability of pedigree history. How plausible is it to unravel the history of a complete unit (chromosome) of inheritance? The second problem deals with reconstructing the recombinational history of a collection of chromosomes.

  9. Progenitors of Recombining Supernova Remnants

    OpenAIRE

    Moriya, Takashi J.

    2012-01-01

    Usual supernova remnants have either ionizing plasma or plasma in collisional ionization equilibrium, i.e., the ionization temperature is lower than or equal to the electron temperature. However, the existence of recombining supernova remnants, i.e., supernova remnants with the ionization temperature higher than the electron temperature, is recently confirmed. One suggested way to have recombining plasma in a supernova remnant is to have a dense circumstellar medium at the time of the superno...

  10. Do mitochondria recombine in humans?

    OpenAIRE

    Eyre-Walker, A

    2000-01-01

    Until very recently, mitochondria were thought to be clonally inherited through the maternal line in most higher animals. However, three papers published in 2000 claimed population-genetic evidence of recombination in human mitochondrial DNA. Here I review the current state of the debate. I review the evidence for the two main pathways by which recombination might occur: through paternal leakage and via a mitochondrial DNA sequence in the nuclear genome. There is no strong evidence for either...

  11. Recombinant snake venom prothrombin activators

    OpenAIRE

    Lövgren, Ann

    2012-01-01

    Three prothrombin activators; ecarin, which was originally isolated from the venom of the saw-scaled viper Echis carinatus, trocarin from the rough-scaled snake Tropidechis carinatus, and oscutarin from the Taipan snake Oxyuranus scutellatus, were expressed in mammalian cells with the purpose to obtain recombinant prothrombin activators that could be used to convert prothrombin to thrombin. We have previously reported that recombinant ecarin can efficiently generate thrombin without the need ...

  12. Delayed recombination and cosmic parameters

    International Nuclear Information System (INIS)

    Current cosmological constraints from cosmic microwave background anisotropies are typically derived assuming a standard recombination scheme, however additional resonance and ionizing radiation sources can delay recombination, altering the cosmic ionization history and the cosmological inferences drawn from the cosmic microwave background data. We show that for recent observations of the cosmic microwave background anisotropy, from the Wilkinson microwave anisotropy probe satellite mission (WMAP) 5-year survey and from the arcminute cosmology bolometer array receiver experiment, additional resonance radiation is nearly degenerate with variations in the spectral index, ns, and has a marked effect on uncertainties in constraints on the Hubble constant, age of the universe, curvature and the upper bound on the neutrino mass. When a modified recombination scheme is considered, the redshift of recombination is constrained to z*=1078±11, with uncertainties in the measurement weaker by 1 order of magnitude than those obtained under the assumption of standard recombination while constraints on the shift parameter are shifted by 1σ to R=1.734±0.028. From the WMAP5 data we obtain the following constraints on the resonance and ionization sources parameters: εαi<0.058 at 95% c.l.. Although delayed recombination limits the precision of parameter estimation from the WMAP satellite, we demonstrate that this should not be the case for future, smaller angular scales measurements, such as those by the Planck satellite mission.

  13. Interstitial deletion of chromosome 1q [del(1)(q24q25.3)] identified by fluorescence in situ hybridization and gene dosage analysis of apolipoprotein A-II, coagulation factor V, and antithrombin III

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Takako; Yamanouchi, Yasuko; Mori, Yosuke [Teikyo Univ. School of Medicine, Tokyo (Japan)] [and others

    1997-01-20

    We report on a 12-month-old Japanese boy with an interstitial deletion of the long-arm of chromosome 1 and meningomyelocele, hydrocephalus, anal atresia, atrial septal defect, left renal agenesis, bilateral cryptorchidism, talipes equinovarus, low birth weight, growth/developmental retardation, and many minor anomalies. By conventional GTG-banding, his karyotype was first interpreted as 46,XY,de1(1)(q23q24), but it was corrected as 46,XY.ish del(1)(q24q25.3) by fluorescence in situ hybridization using 11 known cosmid clones as probes. His serum levels of apolipoprotein A-II (gene symbol: APOA2, previously assigned to 1q21-q23) and coagulation factor V (F5, 1q21-q25) were normal, while serum concentration and activity of antithrombin III (AT3, 1q23-q25.1) was low. The results indicated that localization of APOA2 and F5 are proximal to the deleted region and AT3 is located within the deletion extent in the patient. 16 refs., 4 figs.

  14. The effect of a single recombination event

    DEFF Research Database (Denmark)

    Schierup, Mikkel Heide; Jensen, Thomas Mailund; Wiuf, Carsten

    the effect of a recombination event is the genealogical type of the event and whether SNP variation is present that can reveal the genealogical consequences of the recombination event. Recombination events that only change some branch lengths in the genealogy have a very small, but detectable, effect....... The more lineages left when the recombination event occurs, the larger effect it has, implying that it is mainly young recombination events that we detect when estimating the rate. If the population is growing, though, more lineages are present back in time and relatively more ancient recombination...... shared by these two populations are expected to contribute compared to the effect of private recombination events...

  15. Investigations for designing catalytic recombiners

    International Nuclear Information System (INIS)

    In case of a severe accident in pressurised water reactors (PWR) a high amount of hydrogen up to about 20,000 m3 might be generated and released into the containments. The mixture consisting of hydrogen and oxygen may either burn or detonate, if ignited. In case of detonation the generated shock wave may endanger the components of the plant or the plant itself. Consequently, effective removal of hydrogen is required. The fact that hydrogen and oxygen react exo-thermally on catalytically acting surfaces already at low temperatures generating steam and heat is made use of in catalytic recombiners. They consist of substrates coated with catalyst (mainly platinum or palladium) which are arranged inside a casing. Being passively acting measures, recombiners do not need any additional energy supply. Experimental investigations on catalytic hydrogen recombination are conducted at FZJ (Forschungszentrum Juelich) using three test facilities. The results yield insight in the development potential of contemporary recombiner systems as well as of innovative systems. Detailed investigations on a recombiner section show strong temperature gradients over the surface of a catalytically coated sample. Dependent on the flow velocity, ignition temperature may be reached at the leading edge already at an inlet hydrogen concentration of about 5 vol.-%. The thermal strain of the substrate leads to considerable detachment of catalyst particles probably causing unintended ignition of the flammable mixture. Temperature peaks can be prevented effectively by leaving the first part of the plate uncoated. In order to avoid overheating of the catalyst elements of a recombiner even at high hydrogen concentrations a modular system of porous substrates is proposed. The metallic substrates are coated with platinum at low catalyst densities thus limiting the activity of the single specimen. A modular arrangement of these elements provides high recombination rates over a large hydrogen concentration

  16. Homologous Recombination in Negative Sense RNA Viruses

    OpenAIRE

    Michael Worobey; Guan-Zhu Han

    2011-01-01

    Recombination is an important process that influences biological evolution at many different levels. More and more homologous recombination events have been reported among negative sense RNA viruses recently. While sporadic authentic examples indicate that homologous recombination does occur, recombination seems to be generally rare or even absent in most negative sense RNA viruses, and most of the homologous recombination events reported in the literature were likely generated artificially d...

  17. Recombining WMAP: Constraints on ionizing and resonance radiation at recombination

    International Nuclear Information System (INIS)

    We place new constraints on sources of ionizing and resonance radiation at the epoch of the recombination process using the recent cosmic microwave background temperature and polarization spectra coming from the Wilkinson Microwave Anisotropy Probe (WMAP). We find that non-standard recombination scenarios are still consistent with the current data. In light of this we study the impact that such models can have on the determination of several cosmological parameters. In particular, the constraints on curvature and baryon density appear to be weakly affected by a modified recombination scheme. However, it may affect the current WMAP constraints on inflationary parameters such as the spectral index ns and its running. Physically motivated models, such as those based on primordial black holes or super heavy dark matter decay, are able to provide a good fit to the current data. Future observations in both temperature and polarization will be needed to more stringently test these models

  18. Inhomogeneous recombinations during cosmic reionization

    CERN Document Server

    Sobacchi, Emanuele

    2014-01-01

    By depleting the ionizing photon budget available to expand cosmic HII regions, recombining systems (or Lyman limit systems) can have a large impact during (and following) cosmic reionization. Unfortunately, directly resolving such structures in large-scale reionization simulations is computationally impractical. Instead, here we implement a sub-grid prescription for tracking inhomogeneous recombinations in the intergalactic medium. Building on previous work parameterizing photo-heating feedback on star-formation, we present large-scale, semi-numeric reionization simulations which self-consistently track the local (sub-grid) evolution of both sources and sinks of ionizing photons. Our simple, single-parameter model naturally results in both an extended reionization and a modest, slowly-evolving emissivity, consistent with observations. Recombinations are instrumental in slowing the growth of large HII regions, and damping the rapid rise of the ionizing background in the late stages of (and following) reioniza...

  19. Recombinant snake venom prothrombin activators.

    Science.gov (United States)

    Lövgren, Ann

    2013-01-01

    Three prothrombin activators; ecarin, which was originally isolated from the venom of the saw-scaled viper Echis carinatus, trocarin from the rough-scaled snake Tropidechis carinatus, and oscutarin from the Taipan snake Oxyuranus scutellatus, were expressed in mammalian cells with the purpose to obtain recombinant prothrombin activators that could be used to convert prothrombin to thrombin. We have previously reported that recombinant ecarin can efficiently generate thrombin without the need for additional cofactors, but does not discriminate non-carboxylated prothrombin from biologically active γ-carboxylated prothrombin. Here we report that recombinant trocarin and oscutarin could not efficiently generate thrombin without additional protein co-factors. We confirm that both trocarin and oscutarin are similar to human coagulation Factor X (FX), explaining the need for additional cofactors. Sequencing of a genomic fragment containing 7 out of the 8 exons coding for oscutarin further confirmed the similarity to human FX. PMID:23111318

  20. CRMAGE: CRISPR Optimized MAGE Recombineering

    Science.gov (United States)

    Ronda, Carlotta; Pedersen, Lasse Ebdrup; Sommer, Morten O. A.; Nielsen, Alex Toftgaard

    2016-01-01

    A bottleneck in metabolic engineering and systems biology approaches is the lack of efficient genome engineering technologies. Here, we combine CRISPR/Cas9 and λ Red recombineering based MAGE technology (CRMAGE) to create a highly efficient and fast method for genome engineering of Escherichia coli. Using CRMAGE, the recombineering efficiency was between 96.5% and 99.7% for gene recoding of three genomic targets, compared to between 0.68% and 5.4% using traditional recombineering. For modulation of protein synthesis (small insertion/RBS substitution) the efficiency was increased from 6% to 70%. CRMAGE can be multiplexed and enables introduction of at least two mutations in a single round of recombineering with similar efficiencies. PAM-independent loci were targeted using degenerate codons, thereby making it possible to modify any site in the genome. CRMAGE is based on two plasmids that are assembled by a USER-cloning approach enabling quick and cost efficient gRNA replacement. CRMAGE furthermore utilizes CRISPR/Cas9 for efficient plasmid curing, thereby enabling multiple engineering rounds per day. To facilitate the design process, a web-based tool was developed to predict both the λ Red oligos and the gRNAs. The CRMAGE platform enables highly efficient and fast genome editing and may open up promising prospective for automation of genome-scale engineering. PMID:26797514

  1. Controlled Release from Recombinant Polymers

    OpenAIRE

    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-01-01

    Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and tempor...

  2. Preparing Recombinant Gonad Organ Cultures

    OpenAIRE

    sprotocols

    2014-01-01

    Authors: Blanche Capel and Jordan Batchvarov Corresponding author ([]()) ### INTRODUCTION It can be useful to assay migration between any two adjacent tissues during development. This protocol assays cell migration between the gonad and mesonephros using tissue recombination between genetically marked and unmarked tissue, combined with an organ culture technique. First, agar blocks are prepared in a custom-built mold. The size and sh...

  3. Recombinant DNA: History of the Controversy.

    Science.gov (United States)

    Vigue, Charles L.; Stanziale, William G.

    1979-01-01

    The hazards associated with recombinant DNA research are presented along with some social implications and the development of recombinant DNA research guidelines by the National Institutes of Health. (SA)

  4. Recombinant innovation and endogenous technological transitions

    NARCIS (Netherlands)

    K. Frenken; L.R. Izquierdo; P. Zeppini

    2012-01-01

    We propose a model of technological transitions based on two different types of innovations. Branching innovations refer to technological improvements along a particular path, while recombinant innovations represent fusions of multiple paths. Recombinant innovations create "short-cuts" which reduce

  5. Live recombinant BHV/BRSV vaccine

    NARCIS (Netherlands)

    Keil, G.M.; Rijsewijk, F.A.M.

    1998-01-01

    The present invention refers to synthetic Bovine Respiratory Syncytium virus genes. Also the invention relates to live attenuated Bovine Herpesvirus recombinants carrying such synthetic genes. Furthermore, the invention relates to vaccines based on these live attenuated recombinants, for the protect

  6. Effect of gamma radiation on retroviral recombination.

    OpenAIRE

    Hu, W S; Temin, H M

    1992-01-01

    To elucidate the mechanism(s) of retroviral recombination, we exposed virions to gamma radiation prior to infecting target cells. By using previously described spleen necrosis virus-based vectors containing multiple markers, recombinant proviruses were studied after a single round of retrovirus replication. The current models of retroviral recombination predict that breaking virion RNA should promote minus-strand recombination (forced copy-choice model), decrease or not affect plus-strand rec...

  7. [Recombination in Drosophila in space flight].

    Science.gov (United States)

    Filatova, L P; Vaulina, E N; Lapteva, N Sh; Grozdova, T Ia

    1988-04-01

    An experiment with Drosophila melanogaster males was performed aboard the Artificial Satellite "Kosmos-1667". Mutagenic effects of a 7-day space flight on intergene recombination in chromosome 2 were studied. The space flight factors decreased the frequency of recombination. A model experiment on a laboratory centrifuge demonstrated insignificant increase in recombination frequency caused by acceleration. PMID:3135244

  8. Selection of Recombinant Human Antibodies.

    Science.gov (United States)

    Tomszak, Florian; Weber, Susanne; Zantow, Jonas; Schirrmann, Thomas; Hust, Michael; Frenzel, André

    2016-01-01

    Since the development of therapeutic antibodies the demand of recombinant human antibodies is steadily increasing. Traditionally, therapeutic antibodies were generated by immunization of rat or mice, the generation of hybridoma clones, cloning of the antibody genes and subsequent humanization and engineering of the lead candidates. In the last few years, techniques were developed that use transgenic animals with a human antibody gene repertoire. Here, modern recombinant DNA technologies can be combined with well established immunization and hybridoma technologies to generate already affinity maturated human antibodies. An alternative are in vitro technologies which enabled the generation of fully human antibodies from antibody gene libraries that even exceed the human antibody repertoire. Specific antibodies can be isolated from these libraries in a very short time and therefore reduce the development time of an antibody drug at a very early stage.In this review, we describe different technologies that are currently used for the in vitro and in vivo generation of human antibodies. PMID:27236551

  9. Mechanisms of sister chromatid recombination

    International Nuclear Information System (INIS)

    Studies using T948 as a model system have been carried out aimed at elucidating the mechanism of sister chromatid recombination (SCR). Characterization of U.V. light- and x-ray-induced SCR, the relationiship between SCR induction and DNA repair using rad mutations, and the relationship between SCR induction and the time of cell division using cdc mutations are presented. It has been supposed that SCR is induced at the phase of S-G2 following DNA replication, that postreplication break of DNA strands is strongly involved in the induction of SCR, and that induction type of SCR, i.e., conversion type or recombination type, is dependent upon the type of molecular damage of DNA. (Namekawa, K.)

  10. Recombinations of Busy Beaver Machines

    OpenAIRE

    Bátfai, Norbert

    2009-01-01

    Many programmers belive that Turing-based machines cannot think. We also believe in this, however it is interesting to note that the most sophisticated machines are not programmed by human beings. We have only discovered them. In this paper, using well-known Busy Beaver and Placid Platypus machines, we generate further very similar, but not exactly the same machines. We have found a recombinated BB_5 machine which can make 70.740.809 steps before halting.

  11. Recombinant erythropoietin in clinical practice

    OpenAIRE

    Ng, T; Marx, G.; Littlewood, T; Macdougall, I

    2003-01-01

    The introduction of recombinant human erythropoietin (RHuEPO) has revolutionised the treatment of patients with anaemia of chronic renal disease. Clinical studies have demonstrated that RHuEPO is also useful in various non-uraemic conditions including haematological and oncological disorders, prematurity, HIV infection, and perioperative therapies. Besides highlighting both the historical and functional aspects of RHuEPO, this review discusses the applications of RHuEPO in clinical practice a...

  12. Recombinant antibodies and tumor targeting

    OpenAIRE

    Sheikholvaezin, Ali

    2006-01-01

    Different antibody derived constructs are rapidly advancing as putative tools for treatment of malignant diseases. Antibody engineering has added significant new technologies to modify size, affinities, solubility, stability and biodistribution properties for immunoconjugates. In the present thesis, the aim was to increase our knowledge on how new recombinant antibodies could be tailored to optimize localization to experimental tumors in mice. One hybridoma, producing the monoclonal antibody ...

  13. Workshop on Radio Recombination Lines

    CERN Document Server

    1980-01-01

    Since their first detection 15 years ago, radio recombination lines from several elements have been observed in a wide variety of objects including HII regions, planetary nebulae, molecular clouds, the diffuse interstellar medium, and recently, other galaxies. The observations span almost the entire range from 0.1 to 100 GHz, and employ both single­ djsh and aperture synthesis techniques. The theory of radio recombination lines has also advanced strongly, to the point where it is perhaps one of the best-understood in astro­ physics. In a parallel development, it has become possible over the last decade to study these same highly-excited atoms in the laboratory; this work provides further confirmation of the theoretical framework. However there has been continuing controversy over the astrophysical interpre­ tation of radio recombination line observations, especially regarding the role of stimulated emission. A workshop was held in Ottawa on 24-25 August, 1979, bringing together many of the active scientist...

  14. Effect of gamma radiation on retroviral recombination.

    Science.gov (United States)

    Hu, W S; Temin, H M

    1992-07-01

    To elucidate the mechanism(s) of retroviral recombination, we exposed virions to gamma radiation prior to infecting target cells. By using previously described spleen necrosis virus-based vectors containing multiple markers, recombinant proviruses were studied after a single round of retrovirus replication. The current models of retroviral recombination predict that breaking virion RNA should promote minus-strand recombination (forced copy-choice model), decrease or not affect plus-strand recombination (strand displacement/assimilation model), and shift plus-strand recombination towards the 3' end of the genome. However, we found that while gamma irradiation of virions reduced the amount of recoverable viral RNA, it did not primarily cause breaks. Thus, the frequency of selected recombinants was not significantly altered with greater doses of radiation. In spite of this, the irradiation did decrease the number of recombinants with only one internal template switch. As a result, the average number of additional internal template switches in the recombinant proviruses increased from 0.7 to 1.4 as infectivity decreased to 6%. The unselected internal template switches tended to be 5' of the selected crossover even in the recombinants from irradiated viruses, inconsistent with a plus-strand recombination mechanism. PMID:1602553

  15. Recombinant Factor IX Fc Fusion Protein Maintains Full Procoagulant Properties and Exhibits Prolonged Efficacy in Hemophilia B Mice.

    Directory of Open Access Journals (Sweden)

    Garabet G Toby

    Full Text Available Hemophilia B is an inherited X chromosome-linked disorder characterized by impaired blood clotting owing to the absence of functional coagulation factor IX. Due to the relatively short half-life of factor IX, patients with hemophilia B require frequent factor IX infusions to maintain prophylaxis. We have developed a recombinant factor IX (rFIX fused to the Fc region of IgG (rFIXFc with an extended half-life in animals and humans.Procoagulant properties of rFIXFc and rFIX (BENEFIX® were compared to determine the effect of the Fc region on rFIXFc hemostatic function. Specifically, we assessed rFIXFc activation, intermolecular interactions within the Xase complex, inactivation by antithrombin III (AT and thrombin generation potential compared with rFIX. We also assessed the acute and prophylactic efficacy profiles of rFIXFc and rFIX in vivo in hemophilia B mouse bleeding models.The activation by factor XIa or factor VIIa/tissue factor, inhibition by AT, interaction profiles with phospholipids, affinities for factor VIIIa within the context of the Xase complex, and thrombin generation profiles were similar for rFIXFc and rFIX. Xase complexes formed with either molecule exhibited similar kinetic profiles for factor Xa generation. In acute efficacy models, mice infused with rFIXFc or rFIX were equally protected from bleeding. However, in prophylactic efficacy models, protection from bleeding was maintained approximately three times longer in rFIXFc-dosed mice than in those given rFIX; this prolonged efficacy correlates with the previously observed half-life extension. We conclude that rFIXFc retains critical FIX procoagulant attributes and that the extension in rFIXFc half-life translates into prolonged efficacy in hemophilia B mice.

  16. Current trends of HIV recombination worldwide

    Directory of Open Access Journals (Sweden)

    Katherine A. Lau

    2013-06-01

    Full Text Available One of the major characteristics of HIV-1 is its high genetic variability and extensive heterogeneity. This characteristic is due to its molecular traits, which in turn allows it to vary, recombine, and diversify at a high frequency. As such, it generates complex molecular forms, termed recombinants, which evade the human immune system and so survive. There is no sequence constraint to the recombination pattern as it appears to occur at inter-group (between groups M and O, as well as inter- and intra-subtype within group M. Rapid emergence and active global transmission of HIV-1 recombinants, known as circulating recombinant forms (CRFs and unique recombinant forms (URFs, requires urgent attention. To date, 55 CRFs have been reported around the world. The first CRF01_AE originated from Central Africa but spread widely in Asia. The most recent CRF; CRF55_01B is a recombinant form of CRF01_AE and subtype B, although its origin is yet to be publicly disclosed. HIV-1 recombination is an ongoing event and plays an indispensable role in HIV epidemics in different regions. Africa, Asia and South America are identified as recombination hot-spots. They are affected by continual emergence and co-circulation of newly emerging CRFs and URFs, which are now responsible for almost 20% of HIV-1 infections worldwide. Better understanding of recombinants is necessary to determine their biological and molecular attributes.

  17. Bacteriophage recombination systems and biotechnical applications.

    Science.gov (United States)

    Nafissi, Nafiseh; Slavcev, Roderick

    2014-04-01

    Bacteriophage recombination systems have been widely used in biotechnology for modifying prokaryotic species, for creating transgenic animals and plants, and more recently, for human cell gene manipulation. In contrast to homologous recombination, which benefits from the endogenous recombination machinery of the cell, site-specific recombination requires an exogenous source of recombinase in mammalian cells. The mechanism of bacteriophage evolution and their coexistence with bacterial cells has become a point of interest ever since bacterial viruses' life cycles were first explored. Phage recombinases have already been exploited as valuable genetic tools and new phage enzymes, and their potential application to genetic engineering and genome manipulation, vectorology, and generation of new transgene delivery vectors, and cell therapy are attractive areas of research that continue to be investigated. The significance and role of phage recombination systems in biotechnology is reviewed in this paper, with specific focus on homologous and site-specific recombination conferred by the coli phages, λ, and N15, the integrase from the Streptomyces phage, ΦC31, the recombination system of phage P1, and the recently characterized recombination functions of Yersinia phage, PY54. Key steps of the molecular mechanisms involving phage recombination functions and their application to molecular engineering, our novel exploitations of the PY54-derived recombination system, and its application to the development of new DNA vectors are discussed. PMID:24442504

  18. CRMAGE: CRISPR Optimized MAGE Recombineering

    DEFF Research Database (Denmark)

    Ronda, Carlotta; Pedersen, Lasse Ebdrup; Sommer, Morten Otto Alexander;

    2016-01-01

    A bottleneck in metabolic engineering and systems biology approaches is the lack of efficient genome engineering technologies. Here, we combine CRISPR/Cas9 and λ Red recombineering based MAGE technology (CRMAGE) to create a highly efficient and fast method for genome engineering of Escherichia coli...... assembled by a USER-cloning approach enabling quick and cost efficient gRNA replacement. CRMAGE furthermore utilizes CRISPR/Cas9 for efficient plasmid curing, thereby enabling multiple engineering rounds per day. To facilitate the design process, a web-based tool was developed to predict both the λ Red...

  19. Comparison of 2 synthetically generated recombinant prions

    OpenAIRE

    Zhang, Yi; Wang, Fei; Wang, Xinhe; Zhang, Zhihong; Xu, Yuanyuan; Yu, Guohua; Yuan, Chonggang; Ma, Jiyan

    2014-01-01

    Prion is a protein-conformation-based infectious agent causing fatal neurodegenerative diseases in humans and animals. Our previous studies revealed that in the presence of cofactors, infectious prions can be synthetically generated in vitro with bacterially expressed recombinant prion protein (PrP). Once initiated, the recombinant prion is able to propagate indefinitely via serial protein misfolding cyclic amplification (sPMCA). In this study, we compared 2 separately initiated recombinant p...

  20. Impact of recombination on bacterial evolution

    OpenAIRE

    Didelot, Xavier; Maiden, Martin C. J.

    2010-01-01

    Genetic exchange plays a defining role in the evolution of many bacteria. The recent accumulation of nucleotide sequence data from multiple members of diverse bacterial genera has facilitated comparative studies that have revealed many features of this process. Here we focus on genetic exchange that has involved homologous recombination and illustrate how nucleotide sequence data have furthered our understanding of: (i) the frequency of recombination; (ii) the impact of recombination in diffe...

  1. Recombination rate variation in closely related species

    OpenAIRE

    Smukowski, C S; Noor, M A F

    2011-01-01

    Despite their importance to successful meiosis and various evolutionary processes, meiotic recombination rates sometimes vary within species or between closely related species. For example, humans and chimpanzees share virtually no recombination hotspot locations in the surveyed portion of the genomes. However, conservation of recombination rates between closely related species has also been documented, raising an apparent contradiction. Here, we evaluate how and why conflicting patterns of r...

  2. Role of ubiquitination in meiotic recombination repair

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Programmed and unprogrammed double-strand breaks (DSBs) often arise from such physiological requirements as meiotic recombination, and exogenous insults, such as ionizing radiation (IR). Due to deleterious impacts on genome stability, DSBs must be appropriately processed and repaired in a regulatory manner. Recent investigations have indicated that ubiquitination is a critical factor in DNA damage response and meiotic recombination repair. This review summarizes the effects of proteins and complexes associated with ubiquitination with regard to homologous recombination (HR)-dependent DSB repair.

  3. Consequences of recombination on traditional phylogenetic analysis

    DEFF Research Database (Denmark)

    Schierup, M H; Hein, J

    2000-01-01

    We investigate the shape of a phylogenetic tree reconstructed from sequences evolving under the coalescent with recombination. The motivation is that evolutionary inferences are often made from phylogenetic trees reconstructed from population data even though recombination may well occur (mtDNA or...... recombination leads to a large overestimation of the substitution rate heterogeneity and the loss of the molecular clock. These results are discussed in relation to viral and mtDNA data sets. Udgivelsesdato: 2000-Oct...

  4. RNA recombination in animal and plant viruses.

    OpenAIRE

    Lai, M M

    1992-01-01

    An increasing number of animal and plant viruses have been shown to undergo RNA-RNA recombination, which is defined as the exchange of genetic information between nonsegmented RNAs. Only some of these viruses have been shown to undergo recombination in experimental infection of tissue culture, animals, and plants. However, a survey of viral RNA structure and sequences suggests that many RNA viruses were derived form homologous or nonhomologous recombination between viruses or between viruses ...

  5. Human Insulin from Recombinant DNA Technology

    Science.gov (United States)

    Johnson, Irving S.

    1983-02-01

    Human insulin produced by recombinant DNA technology is the first commercial health care product derived from this technology. Work on this product was initiated before there were federal guidelines for large-scale recombinant DNA work or commercial development of recombinant DNA products. The steps taken to facilitate acceptance of large-scale work and proof of the identity and safety of such a product are described. While basic studies in recombinant DNA technology will continue to have a profound impact on research in the life sciences, commercial applications may well be controlled by economic conditions and the availability of investment capital.

  6. Experimental recombination rates for highly charged ions

    International Nuclear Information System (INIS)

    Recent studies of recombination between free electrons and highly charged ions using electron coolers of heavy-ion storage rings have produced accurate rate coefficients of interest for plasma modeling and diagnostics. Some surprises were discovered which can lead to revisions of recombination models. With bare ions one finds at low energy a strong and puzzling deviation from radiative recombination theory. Dielectronic recombination with C3+, N4+) show that jj coupling gives essential contributions to the cross section also for light ions. (author)

  7. Heterogeneity in recombinant protein production

    DEFF Research Database (Denmark)

    Schalén, Martin; Johanson, Ted; Lundin, Luisa;

    2012-01-01

    A crucial step in biotechnology is the scale-up process. Normally, lab scale verification and optimization of production processes and strains are performed in small reactors with perfect mixing and hence the cells experience a homogenous environment. The gradients that occur in industrial scale...... bioreactors are often not taken into consideration in these experiments. Gradients occur due to insufficient mixing in the reactor, and affect the process in a variety of ways. When cells travel through the reactor and encounter different substrate concentrations, oxygen availability, pH, temperature, etc....... the cell physiology is affected. Cells are stressed, and this may severely affect growth, by-product accumulation, biomass yield and recombinant product yield. The stress caused by exposure to divergent microenvironments, genetic differences of individual cells, differing cell cycle stage and cell age...

  8. Fundamental Studies of Recombinant Hydrogenases

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Michael W

    2014-01-25

    This research addressed the long term goals of understanding the assembly and organization of hydrogenase enzymes, of reducing them in size and complexity, of determining structure/function relationships, including energy conservation via charge separation across membranes, and in screening for novel H2 catalysts. A key overall goal of the proposed research was to define and characterize minimal hydrogenases that are produced in high yields and are oxygen-resistant. Remarkably, in spite of decades of research carried out on hydrogenases, it is not possible to readily manipulate or design the enzyme using molecular biology approaches since a recombinant form produced in a suitable host is not available. Such resources are essential if we are to understand what constitutes a “minimal” hydrogenase and design such catalysts with certain properties, such as resistance to oxygen, extreme stability and specificity for a given electron donor. The model system for our studies is Pyrococcus furiosus, a hyperthermophile that grows optimally at 100°C, which contains three different nickel-iron [NiFe-] containing hydrogenases. Hydrogenases I and II are cytoplasmic while the other, MBH, is an integral membrane protein that functions to both evolve H2 and pump protons. Three important breakthroughs were made during the funding period with P. furiosus soluble hydrogenase I (SHI). First, we produced an active recombinant form of SHI in E. coli by the co-expression of sixteen genes using anaerobically-induced promoters. Second, we genetically-engineered P. furiosus to overexpress SHI by an order of magnitude compared to the wild type strain. Third, we generated the first ‘minimal’ form of SHI, one that contained two rather than four subunits. This dimeric form was stable and active, and directly interacted with a pyruvate-oxidizing enzyme with any intermediate electron carrier. The research resulted in five peer-reviewed publications.

  9. Cell biology of homologous recombination in yeast

    DEFF Research Database (Denmark)

    Eckert-Boulet, Nadine Valerie; Rothstein, Rodney; Lisby, Michael

    2011-01-01

    Homologous recombination is an important pathway for error-free repair of DNA lesions, such as single- and double-strand breaks, and for rescue of collapsed replication forks. Here, we describe protocols for live cell imaging of single-lesion recombination events in the yeast Saccharomyces...

  10. Recombinant organisms for production of industrial products

    OpenAIRE

    Adrio, Jose-Luis; Demain, Arnold L.

    2009-01-01

    A revolution in industrial microbiology was sparked by the discoveries of ther double-stranded structure of DNA and the development of recombinant DNA technology. Traditional industrial microbiology was merged with molecular biology to yield improved recombinant processes for the industrial production of primary and secondary metabolites, protein biopharmaceuticals and industrial enzymes. Novel genetic techniques such as metabolic engineering, combinatorial biosynthesis and molecular breeding...

  11. Theoretic Study of CⅡ Recombination Line

    Institute of Scientific and Technical Information of China (English)

    彭永伦; 王民盛; 韩小英; 李家明

    2004-01-01

    Using the R-matrix method, we carry out theoretical calculations for recombination line λ 8794 A(3d'-3p') of CⅡ, which is important to estimate the abundances of carbon in planetary nebulae. Our calculations are based on three sets of target orbital basis, through which we elucidate the electron correlation and static polarization effects in the dielectronic recombination processes.

  12. Recombinant Vaccinia Virus: Immunization against Multiple Pathogens

    Science.gov (United States)

    Perkus, Marion E.; Piccini, Antonia; Lipinskas, Bernard R.; Paoletti, Enzo

    1985-09-01

    The coding sequences for the hepatitis B virus surface antigen, the herpes simplex virus glycoprotein D, and the influenza virus hemagglutinin were inserted into a single vaccinia virus genome. Rabbits inoculated intravenously or intradermally with this polyvalent vaccinia virus recombinant produced antibodies reactive to all three authentic foreign antigens. In addition, the feasibility of multiple rounds of vaccination with recombinant vaccinia virus was demonstrated.

  13. Electron-ion recombination at low energy

    International Nuclear Information System (INIS)

    The work is based on results obtained with a merged-beams experiment. A beam of electronics with a well characterized density and energy distribution was merged with a fast, monoenergetic ion beam. Results have been obtained for radiative recombination and dielectronic recombination at low relative energies (0 to ∼70eV). The obtained energy resolution was improved by about a factor of 30. High vacuum technology was used to suppress interactions with electrons from the environments. The velocity distribution of the electron beam was determined. State-selective dielectronic-recombination measurements were performable. Recombination processes were studied. The theoretical background for radiative recombination and Kramers' theory are reviewed. The quantum mechanical result and its relation to the semiclassical theory is discussed. Radiative recombination was also measured with several different non-bare ions, and the applicability of the semiclassical theory to non-bare ions was investigated. The use of an effective charge is discussed. For dielectronic recombination, the standard theoretical approach in the isolated resonance and independent-processes approximation is debated. The applicability of this method was tested. The theory was able to reproduce most of the experimental data except when the recombination process was sensitive to couplings between different electronic configurations. The influence of external perturbing electrostatic fields is discussed. (AB) (31 refs.)

  14. Recombinant Swinepox Virus for Veterinary Vaccine Development.

    Science.gov (United States)

    Fan, Hong-Jie; Lin, Hui-Xing

    2016-01-01

    Poxvirus-vectors have been widely used in vaccine development for several important human and animal diseases; some of these vaccines have been licensed and used extensively. Swinepox virus (SPV) is well suited to develop recombinant vaccines because of its large packaging capacity for recombinant DNA, its host range specificity, and its ability to induce appropriate immune responses. PMID:26458836

  15. Molecular requirements for radiation-activated recombination

    International Nuclear Information System (INIS)

    Purpose/Objective: The major stumbling block to successful gene therapy today is poor gene transfer. We hypothesized that ionizing radiation might activate cellular recombination, and so improve stable gene transfer. We further hypothesized that known DNA-damage-repair proteins might also be important in radiation-activated recombination. Materials and Methods: The effect of irradiation on stable gene transfer efficiency was determined in human (A549 and 39F) and rodent (NIH/3T3) cell lines. Continuous low dose rate and multiple radiation fractions were also tested. Nuclear extracts were made and the effect of irradiation on inter-plasmid recombination/ligation determined. Multiple DNA damage-repair deficient cell lines were tested for radiation-activated recombination. Results: A significant radiation dose-dependent improvement in stable plasmid transfection (by as much as 1300 fold) is demonstrated in neoplastic and primary cells. An improvement in transient plasmid transfection is also seen, with as much as 85% of cells transiently expressing b-galactosidase (20-50 fold improvement). Stable transfection is only improved for linearized or nicked plasmids. Cells have improved gene transfer for at least 96 hours after irradiation. Both fractionated and continuous low dose rate irradiation are effective at improving stable gene transfer in mammalian cells, thus making relatively high radiation dose delivery clinically feasible. Inter-plasmid recombination is radiation dose dependent in nuclear extract assays, and the type of overhang (3', 5' or blunt end) significantly affects recombination efficiency and the type of product. The most common end-joining activity involves filling-in of the overhang followed by blunt end ligation. Adenovirus is a linear, double stranded DNA virus. We demonstrate that adenoviral infection efficiency is increased by irradiation. The duration of transgene expression is lengthened because the virus integrates with high efficiency (∼10

  16. V(D)J recombination deficiencies.

    Science.gov (United States)

    de Villartay, Jean-Pierre

    2009-01-01

    V(D)J recombination not only comprises the molecular mechanism that insures diversity of the immune system but also constitutes a critical checkpoint in the developmental program of B- and T-lymphocytes. The analysis of human patients with Severe Combined Immune Deficiency (SCID) has contributed to the understanding of the biochemistry of the V(D)J recombination reaction. The molecular study V(D)J recombination settings in humans, mice and in cellular mutants has allowed to unravel the process of Non Homologous End Joining (NHEJ), one of the key pathway that insure proper repair of DNA double strand breaks (dsb), whether they occur during V(D)J recombination or secondary to other DNA injuries. Two NHEJ factors, Artemis and Cernunnos, were indeed discovered through the study of human V(D)J recombination defective human SCID patients. PMID:19731800

  17. Stress analysis of passive hydrogen autocatalytic recombiner

    International Nuclear Information System (INIS)

    Background: Passive hydrogen autocatalytic recombiner is a device for eliminating hydrogen in the containment of the nuclear power plant when severe accident occurs, avoiding hydrogen explosion. After the Fukushima nuclear accident, the nuclear power plants pay more attention to the role of Passive hydrogen autocatalytic recombiner. Purpose: This paper studies the stresses of passive hydrogen autocatalytic recombiner under the seismic and LOCA conditions, Methods: Modeling by using the finite element software ANSYS, the impacts of airflow load under the LOCA conditions are considered reasonably and the strength of passive hydrogen autocatalytic recombiner is also evaluated according RCC-M, Results: The results show that the model can meet the requirement of the standard document. Conclusions: This paper will provide technical support for stress analysis and evaluation of passive hydrogen autocatalytic recombiner. (authors)

  18. Containment air circulation for optimal hydrogen recombination

    International Nuclear Information System (INIS)

    An accepted first-line defense for hydrogen mitigation is to design for the hydrogen to be rapidly mixed with the containment atmosphere and diluted to below flammability concentrations. Then, as hydrogen continues to be produced in the longer term, recombiners can be used to remove hydrogen: recombiners can be located in forced-air ducts or passive recombiners can be distributed within containment and the heat of recombination used to promote local air circulation. However, this principle does not eliminate the possibility of high hydrogen concentrations at locations removed from the recombiners. An improvement on this strategy is to arrange for a specific, buoyancy-driven, overall circulation of the containment atmosphere such that the recombiners can be located within the recirculation flow, immediately downstream of the hydrogen source. This would make the mixing process more predictable and solve the mass-transfer problem associated with distributed recombiners. Ideally, the recombiners would be located just above the hydrogen source so that the heat of recombination would assist the overall circulation. In this way, the hydrogen would be removed as close as possible to the source, thereby minimizing the amount of hydrogen immediately downstream of the source and reducing the hydrogen concentration to acceptable levels at other locations. Such a strategy requires the containment volume to be divided into an upflow path, past the hydrogen source and the recombiner, and a downflow path to complete the circuit. The flow could be generated actively using fans or passively using buoyancy forces arising from the difference in density of gases in the upfiow and downflow paths; the gases in the downflow path being cooled at an elevated heat sink. (author)

  19. Recombination of cold electrons with cooled ions

    International Nuclear Information System (INIS)

    Recombination, one of the possible reactions of cold electrons with ions, has several important applications, besides being of fundamental interest. Astrophysical objects are studied through their radiation spectra emitted from electron-ion recombination. Plasma modeling and diagnostics are based on the knowledge of recombination cross sections. It is the proposed mechanism for anti-hydrogen production in a trap filled with antiprotons and positrons. The most fundamental process of recombination is radiative recombination (RR): Zq+ + e→ Z(q-1)+ + hν. Here, we discuss measurements of recombination rate coefficients in absolute scale between free electrons and ions at the electron cooler of the CRYRING storage ring at MSL, Stockholm. Surprisingly, there is a consistent disagreement between the measured rates and the rates obtained from theoretical descriptions of RR. It could be shown that this deviation depends on external fields, such as a weak magnetic field in the interaction region. Another effect presented is the enhancement by two orders of magnitude of the recombination rates into a certain quantum state of the atom in a strong laser field. We will discuss these results with respect to their implications for the formation of anti-hydrogen atoms in a Penning trap. (authors)

  20. Optimal Expression Condition of Recombinant RAP

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jie; ZHANG Hong; BI Hao; LIU Zhiguo; GUO Jianli; QU Shen

    2007-01-01

    In order to construct the expression recombinant of human receptor associated protein (RAP), optimize its expression condition and obtain the recombinant protein after expression with high efficiency, two prokaryotic expression vectors-pT7-PL and pET-28a(+) were used to construct the expression recombinant containing RAP cDNA, and the expression efficiency of two kinds of expression E. coli of BL21 strains was compared. The effect of different induction conditions on the expression of recombinant RAP was observed. After recombinant protein was purified with Ni+-nitrilotriacetic acid (Ni+-NTA) affinity chromatogram, its binding ability with microphage was observed. The results showed that two recombinant plasmids both obtained high expression of RAP. The expression levels of RAP in plasmid pT7-PL-RAP in BL21 (DE3, plysS) strain were significantly higher than in BL21 (DE3) strain. The expression of pT7-PL-RAP in the presence of chloramphenicol was higher than in the absence of chloramphenicol, and most of the inducible expressed RAP was soluble. The RAP which was purified by Ni+-NTA resin could strongly bind with the RAW264.7 cells rich in low density lipoprotein receptor (LDLR) family receptors. It was concluded that the expression condition of recombinant RAP was optimized and functional RAP was obtained, which offered a good foundation for the further production of RAP as research tool.

  1. Recombination every day: abundant recombination in a virus during a single multi-cellular host infection.

    Directory of Open Access Journals (Sweden)

    Remy Froissart

    2005-03-01

    Full Text Available Viral recombination can dramatically impact evolution and epidemiology. In viruses, the recombination rate depends on the frequency of genetic exchange between different viral genomes within an infected host cell and on the frequency at which such co-infections occur. While the recombination rate has been recently evaluated in experimentally co-infected cell cultures for several viruses, direct quantification at the most biologically significant level, that of a host infection, is still lacking. This study fills this gap using the cauliflower mosaic virus as a model. We distributed four neutral markers along the viral genome, and co-inoculated host plants with marker-containing and wild-type viruses. The frequency of recombinant genomes was evaluated 21 d post-inoculation. On average, over 50% of viral genomes recovered after a single host infection were recombinants, clearly indicating that recombination is very frequent in this virus. Estimates of the recombination rate show that all regions of the genome are equally affected by this process. Assuming that ten viral replication cycles occurred during our experiment-based on data on the timing of coat protein detection-the per base and replication cycle recombination rate was on the order of 2 x 10(-5 to 4 x 10(-5. This first determination of a virus recombination rate during a single multi-cellular host infection indicates that recombination is very frequent in the everyday life of this virus.

  2. Recombination in narrow-gapped semiconductors

    International Nuclear Information System (INIS)

    In narrow-gapped semiconductors of the type Hgsub(1-x)Cdsub(x)Te as well as in lead chalcogenides and their mixed crystals with energy gaps of some tenths of eV, the band-band recombination processes dominate if the samples are sufficiently perfect in their crystal lattices. The relative importance of the radiative or Auger recombination depends on the width of the energy gap and the charge carrier concentration. In the extreme case of very narrow energy gaps plasmon and one-electron recombination occurs additionally

  3. Recombinant Human Papillomavirus (HPV) Quadrivalent Vaccine

    Science.gov (United States)

    This page contains brief information about recombinant human papillomavirus (HPV) quadrivalent vaccine and a collection of links to more information about the use of this vaccine, research results, and ongoing clinical trials.

  4. Recombinant Human Papillomavirus (HPV) Bivalent Vaccine

    Science.gov (United States)

    This page contains brief information about recombinant human papillomavirus (HPV) bivalent vaccine and a collection of links to more information about the use of this vaccine, research results, and ongoing clinical trials.

  5. Recombinant Human Papillomavirus (HPV) Nonavalent Vaccine

    Science.gov (United States)

    This page contains brief information about recombinant human papillomavirus (HPV) nonavalent vaccine and a collection of links to more information about the use of this vaccine, research results, and ongoing clinical trials.

  6. RNAi and heterochromatin repress centromeric meiotic recombination

    DEFF Research Database (Denmark)

    Ellermeier, Chad; Higuchi, Emily C; Phadnis, Naina;

    2010-01-01

    During meiosis, the formation of viable haploid gametes from diploid precursors requires that each homologous chromosome pair be properly segregated to produce an exact haploid set of chromosomes. Genetic recombination, which provides a physical connection between homologous chromosomes, is....... Surprisingly, one mutant derepressed for recombination in the heterochromatic mating-type region during meiosis and several mutants derepressed for centromeric gene expression during mitotic growth are not derepressed for centromeric recombination during meiosis. These results reveal a complex relation between...... types of repression by heterochromatin. Our results also reveal a previously undemonstrated role for RNAi and heterochromatin in the repression of meiotic centromeric recombination and, potentially, in the prevention of birth defects by maintenance of proper chromosome segregation during meiosis....

  7. Genetic Analyses of Meiotic Recombination in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Meiosis is essential for sexual reproduction and recombination is a critical step required for normal meiosis. Understanding the underlying molecular mechanisms that regulate recombination ie important for medical, agricultural and ecological reasons. Readily available molecular and cytological tools make Arabidopsis an excellent system to study meiosis. Here we review recent developments in molecular genetic analyses on meiotic recombination. These Include studies on plant homologs of yeast and animal genes, as well as novel genes that were first identified in plants. The characterizations of these genes have demonstrated essential functions from the initiation of recombination by double-strand breaks to repair of such breaks, from the formation of double-Holliday junctions to possible resolution of these junctions, both of which are critical for crossover formation. The recent advances have ushered a new era in plant meiosis, in which the combination of genetics, genomics, and molecular cytology can uncover important gene functions.

  8. Recombinant vaccines: experimental and applied aspects

    DEFF Research Database (Denmark)

    Lorenzen, Niels

    1999-01-01

    Development of vaccines for aquaculture fish represent an important applied functional aspect of fish immunology research. Particularly in the case of recombinant vaccines, where a single antigen is usually expected to induce immunity to a specific pathogen, knowledge of mechanisms involved in...... induction of a protective immune response may become vital. The few recombinant vaccines licensd so far, despite much research during the last decade, illustrate that this is not a straightforward matter. However, as vaccine technology as well as our knowledge of the fish immune system is steadily improved......, these fields will open up a number of interesting research objectives of mutual benefit. Recent aspects of recombinant protein vaccines, live recombinant vaccines and DNA vaccines are discussed....

  9. Efficient generation of recombinant adenoviral vectors by Cre-lox recombination in vitro.

    OpenAIRE

    Aoki, K.; Barker, C.; Danthinne, X; Imperiale, M J; Nabel, G. J.

    1999-01-01

    BACKGROUND: Although recombinant adenovirus vectors are attractive for use in gene expression studies and therapeutic applications, the construction of these vectors remains relatively time-consuming. We report here a strategy that simplifies the production of adenoviruses using the Cre-loxP system. MATERIALS AND METHODS: Full-length recombinant adenovirus DNA was generated in vitro by Cre-mediated recombination between loxP sites in a linearized shuttle plasmid containing a transgene and ade...

  10. Intermolecular recombination assay for mammalian cells that produces recombinants carrying both homologous and nonhomologous junctions.

    OpenAIRE

    Brouillette, S; Chartrand, P

    1987-01-01

    We present an intermolecular recombination assay for mammalian cells that does not involve the reconstitution of a selectable marker. It is based on the generation of a shuttle vector by recombination between a bacterial and a mammalian vector. The recombinants can thus be amplified in mammalian cells, isolated by plasmid rescue in an Escherichia coli RecA- host, and identified by in situ hybridization, by using mammalian vector sequences as probes. Since both parental molecules can share def...

  11. Signals From the Epoch of Cosmological Recombination

    OpenAIRE

    Sunyaev, R. A.; Chluba, J.

    2009-01-01

    The physical ingredients to describe the epoch of cosmological recombination are amazingly simple and well-understood. This fact allows us to take into account a very large variety of physical processes, still finding potentially measurable consequences for the energy spectrum and temperature anisotropies of the Cosmic Microwave Background (CMB). In this contribution we provide a short historical overview in connection with the cosmological recombination epoch and its connection to the CMB. A...

  12. Tunnel surface recombination in optoelectronic device modeling

    Science.gov (United States)

    Ptashchenko, Alexander A.; Ptashchenko, Fedor A.

    1997-08-01

    The rate of tunnel surface recombination (TSR) in a p-n structure has been calculated as a function of the excitation level and temperature in a semiclassical approximation under the assumption that the excess energy of a recombining electron is transferred to phonons or to a photon. The approximating analytical expressions obtained are applied in calculations of the effect of TSR on the characteristics of photodiodes, solar cells, light-emitting diodes and diode lasers.

  13. Recombinant DNA production of spider silk proteins

    OpenAIRE

    Tokareva, Olena; Michalczechen-Lacerda, Valquíria A; Rech, Elíbio L; Kaplan, David L.

    2013-01-01

    Spider dragline silk is considered to be the toughest biopolymer on Earth due to an extraordinary combination of strength and elasticity. Moreover, silks are biocompatible and biodegradable protein-based materials. Recent advances in genetic engineering make it possible to produce recombinant silks in heterologous hosts, opening up opportunities for large-scale production of recombinant silks for various biomedical and material science applications. We review the current strategies to produce...

  14. Algae-based oral recombinant vaccines

    OpenAIRE

    Specht, Elizabeth A.; Mayfield, Stephen P

    2014-01-01

    Recombinant subunit vaccines are some of the safest and most effective vaccines available, but their high cost and the requirement of advanced medical infrastructure for administration make them impractical for many developing world diseases. Plant-based vaccines have shifted that paradigm by paving the way for recombinant vaccine production at agricultural scale using an edible host. However, enthusiasm for “molecular pharming” in food crops has waned in the last decade due to difficulty in ...

  15. Dielectronic recombination of hydrogen-like ions

    International Nuclear Information System (INIS)

    Decay dynamics of dielectronic recombination (DR) processes of H-like titanium ions was investigated with an electron beam ion trap. In the DR of H-like ions a K-shell vacancy is available even after the decay of the doubly excited state produced by the recombination. Therefore secondary X-ray emission is possible. An observed X-ray spectrum of DR obtained in the present experiment was well reproduced theoretically by taking into account the secondary X-rays

  16. Recombination-deficient mutant of Streptococcus faecalis.

    OpenAIRE

    Yagi, Y; Clewell, D B

    1980-01-01

    An ultraviolet radiation-sensitive derivative of Streptococcus faecalis strain JH2-2 was isolated and found to be deficient in recombination, using a plasmid-plasmid recombination system. The strain was sensitive to chemical agents which interact with deoxyribonucleic acid and also underwent deoxyribonucleic acid degradation after ultraviolet irradiation. Thus, the mutant has properties similar to those of recA strains of Escherichia coli.

  17. Recombination of U92+ ions with electrons

    International Nuclear Information System (INIS)

    Recombination of fully stripped U92+ ions with electrons has been investigated at the Experimental Storage Ring (ESR) in Darmstadt. Absolute recombination rate coefficients have been measured for relative energies from 0 to 33 eV. For energies greater than 20 meV the experimental result is well described by the theory for radiative recombination (RR). Below 20 meV the experimental rate increasingly exceeds the RR calculation as observed previously in the recombination of light bare ions as well as of Bi83+. This low-energy rate enhancement is shown to scale as Z2.6 for bare ions, where Z is the atomic number of the ion. The U92+ recombination rate enhancement is insensitive to changes of the electron density. Variation of the magnetic guiding field strength from 80 mT to 120 mT resulted in oscillations of the recombination rate at 0 eV. The oscillations are partly attributed to changes of the transverse electron temperature accompanying the change of the magnetic guiding field strength; partly they may be caused by uncompensated small changes of the interaction angle between the two beams. (orig.)

  18. The functional study of antithrombin L99 mutation%抗凝血酶L99氨基酸位点突变对其功能的影响

    Institute of Scientific and Technical Information of China (English)

    郁婷婷; 戴菁; 丁秋兰; 傅启华; 王学锋

    2014-01-01

    Objective To study the molecular mechanisms of inherited antithrombin (AT)defiency caused by AT L99 mutation.Methods Wild type (WT),L99V,L99A,L99I and L99S AT were purified from drosophila expression system.The binding capacity of AT and the low molecular weight heparin sodium was analyzed by the heparin binding assay.Surface plasmon resonance (SPR) was used to detect the binding ability of AT to thrombin (F Ⅱ a) or AT to coagulation factor X a (F X a).The activity of AT (AT∶ A) was detected by chromogenic assay.Results The purified WT and mutant AT were at the same size.No additional band was observed by coomassie blue staining and western blot assay.Compared to the WT AT,the binding abilities of the low molecular weight heparin sodium to the AT L99V,L99A,L99I and L99S were (44.8±3.6)%,(118.9±14.0)%,(15.2±8.8)%,and (23.0±8.2)%,respectively.The binding abilities of F Ⅱ a to AT L99V,L99A,L99I and L99S were 13%,57%,3%,and 29%,while the binding of F X a to AT L99V,L99A,L99I and L99S were 7%,51%,1%,and 25%.The AT∶A of WT,L99V,L99A,L99I and L99S AT were 146.5%,21.4%,120.9%,10.8%,and 39.0%,respectively.Conclusion The binding abilities of AT to heparin,F Ⅱ a and F X a were damaged by the L99 mutation,which resulted in decreased AT∶ A and inherited AT deficiency.%目的 研究抗凝血酶(AT)L99氨基酸位点突变导致遗传性AT缺陷症的分子机制.方法 利用果蝇细胞表达系统表达纯化野生型AT以及L99V、L99A、L99I和L99S等突变型AT蛋白;采用肝素结合实验检测重组AT蛋白与低分子量肝素钠的结合能力;采用表面等离子共振(SPR)技术检测重组AT蛋白与凝血酶(FⅡa)及活化凝血因子X(FXa)的结合能力;将野生型及各突变型AT蛋白的浓度调整至正常AT血浆浓度后,采用发色底物法检测重组AT蛋白活性.结果 考马斯亮蓝染色及免疫印迹法显示各突变蛋白与野生型AT蛋白大小一致,未见明显杂带.

  19. Recombination analysis based on the complete genome of bocavirus

    Directory of Open Access Journals (Sweden)

    Chen Shengxia

    2011-04-01

    Full Text Available Abstract Bocavirus include bovine parvovirus, minute virus of canine, porcine bocavirus, gorilla bocavirus, and Human bocaviruses 1-4 (HBoVs. Although recent reports showed that recombination happened in bocavirus, no systematical study investigated the recombination of bocavirus. The present study performed the phylogenetic and recombination analysis of bocavirus over the complete genomes available in GenBank. Results confirmed that recombination existed among bocavirus, including the likely inter-genotype recombination between HBoV1 and HBoV4, and intra-genotype recombination among HBoV2 variants. Moreover, it is the first report revealing the recombination that occurred between minute viruses of canine.

  20. Performance testing of passive autocatalytic recombiners (PARs)

    International Nuclear Information System (INIS)

    Passive autocatalytic recombiners (PARs) have been under consideration in the U.S. as a combustible gas control system in advanced light water reactor (ALWR) containments for design basis and severe accidents. PARs do not require a source of power. Instead they use palladium or platinum as a catalyst to recombine hydrogen and oxygen gases into water vapor upon contact with the catalyst. Energy from the recombination of hydrogen with oxygen is released at a relatively slow but continuous rate into the containment which prevents the pressure from becoming too high. The heat produced creates strong buoyancy effects which increases the influx of the surrounding gases to the recombiner. These natural convective flow currents promote mixing of combustible gases in the containment. PARs are self-starting and self-feeding under a very wide range of conditions. The recombination rate of the PAR system needs to be great enough to keep the concentration of hydrogen (or oxygen) below acceptable limits. There are several catalytic recombiner concepts under development worldwide. The USNRC is evaluating a specific design of a PAR which is in an advanced stage of engineering development and has been proposed for ALWR designs. Sandia National laboratories (SNL), under the sponsorship and the direction of the USNRC, is conducting an experimental program to evaluate the performance of PARs. The PAR will be tested at the SURTSEY facility at SNL. The test plan currently includes the following experiments: experiments will be conducted to define the startup characteristics of PARs (i.e., to define what is the lowest hydrogen concentration that the PAR starts recombining the hydrogen with oxygen); experiments will be used to define the hydrogen depletion rate of PARs as a function of hydrogen concentration; and experiments will be used to define the PAR performance in the presence of high concentrations of steam. (author)

  1. Inhibition of coagulation factors by recombinant barley serpin BSZx

    DEFF Research Database (Denmark)

    Dahl, Søren Weis; Rasmussen, S.K.; Petersen, L..C.;

    1996-01-01

    leukocytes, a fungal trypsin and three subtilisins, Thrombin, plasma kallikrein, factor VIIa/tissue factor and factor Xa were inhibited by BSZx at heparin independent association rates (k(ass)) of 4.5 x 10(3)-1.3 x 10(5) M(-1) s(-1) at 22 degrees C. Only factor Xa turned a significant fraction of BSZx over...... as substrate, Complexes of these proteinase with BSZx resisted boiling in SDS, and amino acid sequencing showed that cleavage in the reactive center loop only occurred after P-1 Arg. Activated protein C and leukocyte elastase were slowly inhibited by BSZx (k(ass) = 1-2 x 10(2) M(-1) s(-1)) whereas...... factor XIIa, urokinase and tissue type plasminogen activator, plasmin and pancreas kallikrein and elastase were not or only weakly affected, The inhibition pattern with mammalian proteinases reveal a specificity of BSZx similar to that of antithrombin III. Trypsin from Fusarium was not inhibited while...

  2. Graded Recombination Layers for Multijunction Photovoltaics

    KAUST Repository

    Koleilat, Ghada I.

    2012-06-13

    Multijunction devices consist of a stack of semiconductor junctions having bandgaps tuned across a broad spectrum. In solar cells this concept is used to increase the efficiency of photovoltaic harvesting, while light emitters and detectors use it to achieve multicolor and spectrally tunable behavior. In series-connected current-matched multijunction devices, the recombination layers must allow the hole current from one cell to recombine, with high efficiency and low voltage loss, with the electron current from the next cell. We recently reported a tandem solar cell in which the recombination layer was implemented using a progression of n-type oxides whose doping densities and work functions serve to connect, with negligible resistive loss at solar current densities, the constituent cells. Here we present the generalized conditions for design of efficient graded recombination layer solar devices. We report the number of interlayers and the requirements on work function and doping of each interlayer, to bridge an work function difference as high as 1.6 eV. We also find solutions that minimize the doping required of the interlayers in order to minimize optical absorption due to free carriers in the graded recombination layer (GRL). We demonstrate a family of new GRL designs experimentally and highlight the benefits of the progression of dopings and work functions in the interlayers. © 2012 American Chemical Society.

  3. Human recombinant lysosomal enzymes produced in microorganisms.

    Science.gov (United States)

    Espejo-Mojica, Ángela J; Alméciga-Díaz, Carlos J; Rodríguez, Alexander; Mosquera, Ángela; Díaz, Dennis; Beltrán, Laura; Díaz, Sergio; Pimentel, Natalia; Moreno, Jefferson; Sánchez, Jhonnathan; Sánchez, Oscar F; Córdoba, Henry; Poutou-Piñales, Raúl A; Barrera, Luis A

    2015-01-01

    Lysosomal storage diseases (LSDs) are caused by accumulation of partially degraded substrates within the lysosome, as a result of a function loss of a lysosomal protein. Recombinant lysosomal proteins are usually produced in mammalian cells, based on their capacity to carry out post-translational modifications similar to those observed in human native proteins. However, during the last years, a growing number of studies have shown the possibility to produce active forms of lysosomal proteins in other expression systems, such as plants and microorganisms. In this paper, we review the production and characterization of human lysosomal proteins, deficient in several LSDs, which have been produced in microorganisms. For this purpose, Escherichia coli, Saccharomyces cerevisiae, Pichia pastoris, Yarrowia lipolytica, and Ogataea minuta have been used as expression systems. The recombinant lysosomal proteins expressed in these hosts have shown similar substrate specificities, and temperature and pH stability profiles to those produced in mammalian cells. In addition, pre-clinical results have shown that recombinant lysosomal enzymes produced in microorganisms can be taken-up by cells and reduce the substrate accumulated within the lysosome. Recently, metabolic engineering in yeasts has allowed the production of lysosomal enzymes with tailored N-glycosylations, while progresses in E. coli N-glycosylations offer a potential platform to improve the production of these recombinant lysosomal enzymes. In summary, microorganisms represent convenient platform for the production of recombinant lysosomal proteins for biochemical and physicochemical characterization, as well as for the development of ERT for LSD. PMID:26071627

  4. Recombinant human erythropoietin in sports: a review

    Directory of Open Access Journals (Sweden)

    Rafael Maia de Almeida Bento

    2003-06-01

    Full Text Available Erythropoietin is an endogenous hormone of glicoproteic nature secreted by the kidneys and is the main regulator of the erythropoiesis. An alteration in its production generates a disturbance in the plasmatic concentration giving rise to several types of pathologies related to the hematopoietic system. The recombinant forms of erythropoietin have indiscriminately been used by athletes, mainly in endurance sports, by increasing the erythrocytes concentration, generating a better delivery of oxygen to the muscle tissue. The administration of recombinant erythropoietin was prohibited by the International Olympic Committee and its use considered as doping. This review has the intention to describe the physical, biological and pharmacokinetic properties of the endogenous erythropoietin, as well as its recombinant form, describing also its use in sports and the process of searching methodologies for its detection in doping control.

  5. Jet fragmentation via recombination of parton showers

    Science.gov (United States)

    Han, Kyong Chol; Fries, Rainer J.; Ko, Che Ming

    2016-04-01

    We propose to model hadronization of parton showers in QCD jets through a hybrid approach involving quark recombination and string fragmentation. This is achieved by allowing gluons at the end of the perturbative shower evolution to undergo a nonperturbative splitting into quark and antiquark pairs, then applying a Monte Carlo version of instantaneous quark recombination, and finally subjecting remnant quarks (those which have not found a recombination partner) to Lund string fragmentation. When applied to parton showers from the pythia Monte Carlo event generator, the final hadron spectra from our calculation compare quite well to pythia jets that have been hadronized with the default Lund string fragmentation. Our new approach opens up the possibility to generalize hadronization to jets embedded in a quark gluon plasma.

  6. Comparison of recombination models in organic bulk heterojunction solar cells

    International Nuclear Information System (INIS)

    Recombination in bulk-heterojunction (BHJ) organic solar cells is the key loss mechanism, and it directly affects characteristic parameters such as power conversion efficiency, short-circuit current, open-circuit voltage, and fill factor. However, which recombination mechanism dominates the loss in organic materials is unclear at present. In this work, we simulate state-of-art BHJ solar cells using five recombination models, including direct recombination, Langevin recombination, charge transfer state recombination, trap-assisted recombination, and recombination via tail. All processes are strongly dependent on charge carrier mobility and exhibit a similar recombination distribution in active layer. For high mobilities, all models present a similar behavior along with the increased mobilities, whereas, there are slight differences in open-circuit voltage between trap/tail model and other ones at lower mobilities, resulting from the interaction between photo-carriers and dark-carriers

  7. An antithrombin-dependent sulfated polysaccharide isolated from the green alga Caulerpa cupressoides has in vivo anti- and prothrombotic effects Um polissacarídeo sulfatado dependente de antitrombina isolado da alga verde Caulerpa cupressoides possui efeitos anti- e pró-trombótico in vivo

    Directory of Open Access Journals (Sweden)

    José Ariévilo Gurgel Rodrigues

    2011-04-01

    Full Text Available Red algae sulfated polysaccharides (SPs have been widely described as anticoagulant and antithrombotic agents; however no description of antithrombotic activity regarding green algae SPs has been reported. Caulerpa cupressoides (Chlorophyta has three different SPs fractions (SP1, SP2 and SP3. We investigated the effects of SP2 on thrombin activity by antithrombin and in an experimental model of venous thrombosis in rats. The inhibition of thrombin assay was evaluated using antithrombin (AT in the presence of SP2 and the antithrombotic activity was investigated in rats with thromboplastin as the thrombogenic stimulus. The anticoagulant effects of SP2 are suggested be due to the potentiation of thrombin inhibition by antithrombin (IC50 ~ 10.0µg mL-1 and this mechanism of interaction is different when compared to other studied Caulerpa polysaccharides. SP2 exhibited antithrombotic effects at doses of 1.0 and 2.0mg kg-1 body weight, but at higher doses (>2.0mg kg-1 body weight this polysaccharide revert the antithrombotic property. No hemorrhagic effect (2.0mg kg-1 was observed. As occurs with red algae SPs, these results indicate that green algae SPs are also capable of exhibiting different in vivo properties.Os polissacarídeos sulfatados (PSs de algas vermelhas têm sido relatados mundialmente como agentes anticoagulantes e antitrombóticos. Entretanto, nenhuma descrição de atividade antitrombótica tem sido relacionada com os PSs de algas verdes. A clorofícea Caulerpa cupressoides possui três frações de PSs (PS1; PS2 e PS3. Dessa forma, objetivou-se investigar os efeitos da fração PS2 sobre a atividade da trombina por antitrombina e usando um modelo experimental de trombose venosa em ratos. O ensaio de inibição da trombina foi avaliado usando a antitrombina (AT na presença de PS2 e a atividade antitrombótica foi investigada em ratos, usando a tromboplastina como o estímulo trombogênico. Os efeitos anticoagulantes de PS2 devem

  8. SIR epidemics in monogamous populations with recombination

    CERN Document Server

    Zanette, Damián H

    2011-01-01

    We study the propagation of an SIR (susceptible-infectious-recovered) disease over an agent population which, at any instant, is fully divided into couples of agents. Couples are occasionally allowed to exchange their members. This process of couple recombination can compensate the instantaneous disconnection of the interaction pattern and thus allow for the propagation of the infection. We study the incidence of the disease as a function of its infectivity and of the recombination rate of couples, thus characterizing the interplay between the epidemic dynamics and the evolution of the population's interaction pattern.

  9. Quantum Electrodynamics Theory of Laser Assisted Recombination

    Institute of Scientific and Technical Information of China (English)

    敖淑艳; 程太旺; 李晓峰; 潘守甫; 傅盘铭

    2003-01-01

    Using a formal scattering theoretical approach, we develop a nonperturbative quantum electrodynamics theory to describe laser assisted recombination (LAR), in which an electron initially in the quantized Volkov state recombines with an ion and emits a high-energy photon with frequency defined by energy conservation laws.The transition probability is expressed as an analytic closed form and the spectrum of LAR reflects mainly the properties of general Bessel functions. For the case of a fast electron the LAR spectrum is confined in a well-defined range, while for a slow electron, the LAR spectrum exhibits a double-plateau structure.

  10. Recombinant microorganisms for increased production of organic acids

    Science.gov (United States)

    Yi, Jian; Kleff, Susanne; Guettler, Michael V

    2013-04-30

    Disclosed are recombinant microorganisms for producing organic acids. The recombinant microorganisms express a polypeptide that has the enzymatic activity of an enzyme that is utilized in the pentose phosphate cycle. The recombinant microorganism may include recombinant Actinobacillus succinogenes that has been transformed to express a Zwischenferment (Zwf) gene. The recombinant microorganisms may be useful in fermentation processes for producing organic acids such as succinic acid and lactic acid. Also disclosed are novel plasmids that are useful for transforming microorganisms to produce recombinant microorganisms that express enzymes such as Zwf.

  11. Radiative recombination of excitons in amorphous semiconductors

    International Nuclear Information System (INIS)

    A theory for calculating the radiative lifetime of excitons in amorphous semiconductors is presented. Four possibilities of excitonic radiative recombination are considered and the corresponding rates are derived at thermal equilibrium. The radiative lifetime is calculated from the inverse of the maximum rate for all the four possibilities. Results agree very well with experiments

  12. Genetic Recombination as a Chemical Reaction Network

    OpenAIRE

    Müller, Stefan; Hofbauer, Josef

    2015-01-01

    The process of genetic recombination can be seen as a chemical reaction network with mass-action kinetics. We review the known results on existence, uniqueness, and global stability of an equilibrium in every compatibility class and for all rate constants, from both the population genetics and the reaction networks point of view.

  13. Science: The Recombinant DNA Advisory Committee.

    Science.gov (United States)

    Wright, Susan

    1979-01-01

    Reports on the status of the Recombinant DNA Advisory Committee (RAC) and attempts to rationalize Suburban Highway Policy. Effective communication among members of the RAC is a current problem facing the committee. A federal transportation priority spending policy is suggested during these times of money and fuel shortages. (MA)

  14. Recombinant Bovine Growth Hormone Criticism Grows.

    Science.gov (United States)

    Gaard, Greta

    1995-01-01

    Discusses concerns related to the use of recombinant bovine growth hormone in the United States and other countries. Analyses the issue from the perspectives of animal rights, human health, world hunger, concerns of small and organic farmers, costs to the taxpayer, and environmental questions. A sidebar discusses Canadian review of the hormone.…

  15. Vaccine development using recombinant DNA technology

    Science.gov (United States)

    Vaccines induce an immune response in the host that subsequently recognizes infectious agents and helps fight off the disease; vaccines must do this without causing the disease. This paper reviews the development of recombinant DNA technologies as a means of providing new ways for attenuating diseas...

  16. Selected techniques in recombinant DNA technology

    International Nuclear Information System (INIS)

    Recombined DNA technology comprises a complex of techniques in the fields of nucleic acid biochemistry and molecular biology. This presentation gives an introduction, a brief description and example of the procedures of some of the basic techniques in the DNA cloning work currently used. 8 refs

  17. Recombinant DNA: Scientific and Social Perspectives.

    Science.gov (United States)

    Vandegrift, Vaughn

    1979-01-01

    This article is designed to inform chemical educators not engaged in this technology as to the nature and methods used in the technology, the reasons for scientific and social concern, and the attempts made to assuage concerns involving recombinant DNA research. (author/BB)

  18. Production and delivery of recombinant subunit vaccines

    OpenAIRE

    Andersson, Christin

    2000-01-01

    Recombinant strategies are today dominating in thedevelopment of modern subunit vaccines. This thesis describesstrategies for the production and recovery of protein subunitimmunogens, and how genetic design of the expression vectorscan be used to adapt the immunogens for incorporation intoadjuvant systems. In addition, different strategies fordelivery of subunit vaccines by RNA or DNA immunization havebeen investigated. Attempts to create general production strategies forrecombinant protein i...

  19. Asthma and Therapeutics: Recombinant Therapies in Asthma

    Directory of Open Access Journals (Sweden)

    Cockcroft Donald W

    2005-03-01

    Full Text Available Abstract Numerous recombinant therapies are being investigated for the treatment of asthma. This report reviews the current status of several of these novel agents. Anti-immunoglobulin (IgE (omalizumab, Xolair markedly inhibits all aspects of the allergen challenge in subjects who have reduction of free serum IgE to undetectable levels. Several clinical studies in atopic asthma have demonstrated benefit by improved symptoms and lung function and a reduction in corticosteroid requirements. Early use in atopic asthmatics may be even more effective. Several approaches target interleukin (IL-4. Soluble IL-4 receptor has been shown to effectively replace inhaled corticosteroid; further studies are under way. Recombinant anti-IL-5 and recombinant IL-12 inhibit blood and sputum eosinophils and allergen-induced eosinophilia without any effect on airway responsiveness, allergen-induced airway responses, or allergen-induced airway hyperresponsiveness. Efalizumab, a recombinant antibody that inhibits lymphocyte trafficking, is effective in psoriasis. A bronchoprovocation study showed a reduction in allergen-induced late asthmatic response and allergen-induced eosinophilia, which suggests that it should be effective in clinical asthma. These exciting novel therapies provide not only promise of new therapies for asthma but also valuable tools for investigation of asthma mechanisms.

  20. Catalytic hydrogen recombination for nuclear containments

    International Nuclear Information System (INIS)

    Catalytic recombiners appear to be a credible option for hydrogen mitigation in nuclear containments. The passive operation, versatility and ease of back fitting are appealing for existing stations and new designs. Recently, a generation of wet-proofed catalyst materials have been developed at AECL which are highly specific to H2-O2, are active at ambient temperatures and are being evaluated for containment applications. Two types of catalytic recombiners were evaluated for hydrogen removal in containments based on the AECL catalyst. The first is a catalytic combustor for application in existing air streams such as provided by fans or ventilation systems. The second is an autocatalytic recombiner which uses the enthalpy of reaction to produce natural convective flow over the catalyst elements. Intermediate-scale results obtained in 6 m3 and 10 m3 spherical and cylindrical vessels are given to demonstrate self-starting limits, operating limits, removal capacity, scaling parameters, flow resistance, mixing behaviour in the vicinity of an operating recombiner and sensitivity to poisoning, fouling and radiation. (author). 13 refs., 10 figs

  1. Recombinant protein blends: silk beyond natural design.

    Science.gov (United States)

    Dinjaski, Nina; Kaplan, David L

    2016-06-01

    Recombinant DNA technology and new material concepts are shaping future directions in biomaterial science for the design and production of the next-generation biomaterial platforms. Aside from conventionally used synthetic polymers, numerous natural biopolymers (e.g., silk, elastin, collagen, gelatin, alginate, cellulose, keratin, chitin, polyhydroxyalkanoates) have been investigated for properties and manipulation via bioengineering. Genetic engineering provides a path to increase structural and functional complexity of these biopolymers, and thereby expand the catalog of available biomaterials beyond that which exists in nature. In addition, the integration of experimental approaches with computational modeling to analyze sequence-structure-function relationships is starting to have an impact in the field by establishing predictive frameworks for determining material properties. Herein, we review advances in recombinant DNA-mediated protein production and functionalization approaches, with a focus on hybrids or combinations of proteins; recombinant protein blends or 'recombinamers'. We highlight the potential biomedical applications of fibrous protein recombinamers, such as Silk-Elastin Like Polypeptides (SELPs) and Silk-Bacterial Collagens (SBCs). We also discuss the possibility for the rationale design of fibrous proteins to build smart, stimuli-responsive biomaterials for diverse applications. We underline current limitations with production systems for these proteins and discuss the main trends in systems/synthetic biology that may improve recombinant fibrous protein design and production. PMID:26686863

  2. Algae-based oral recombinant vaccines

    Directory of Open Access Journals (Sweden)

    Elizabeth A Specht

    2014-02-01

    Full Text Available Recombinant subunit vaccines are some of the safest and most effective vaccines available, but their high cost and the requirement of advanced medical infrastructure for administration make them impractical for many developing world diseases. Plant-based vaccines have shifted that paradigm by paving the way for recombinant vaccine production at agricultural scale using an edible host. However, enthusiasm for molecular pharming in food crops has waned in the last decade due to difficulty in developing transgenic crop plants and concerns of contaminating the food supply. Microalgae are poised to become the next candidate in recombinant subunit vaccine production, and they present several advantages over terrestrial crop plant-based platforms including scalable and contained growth, rapid transformation, easily obtained stable cell lines, and consistent transgene expression levels. Algae have been shown to accumulate and properly fold several vaccine antigens, and efforts are underway to create recombinant algal fusion proteins that can enhance antigenicity for effective orally-delivered vaccines. These approaches have the potential to revolutionize the way subunit vaccines are made and delivered – from costly parenteral administration of purified protein, to an inexpensive oral algae tablet with effective mucosal and system immune reactivity.

  3. Recombination times in germanium under high pressure

    International Nuclear Information System (INIS)

    The influence of pressure on a well defined recombination process was studied. The centres were introduced by γirradiation and the lifetime determined by the decay time of photoconductivity. An optical pressure vessel is described which allows for a hydrostatic variation of 3000 bars. The diffusion constant and lifetime measurements are presented and analysed. (V.J.C.)

  4. Experimental Mg IX photo recombination rate coefficient

    International Nuclear Information System (INIS)

    The rate coefficient for radiative and dielectronic recombination of beryllium-like magnesium ions was measured with high resolution at the Heidelberg heavy-ion storage ring TSR. In the electron-ion collision energy range 0-207 eV resonances due to 2s → 2p (ΔN = 0) and 2s → 3l (ΔN = 1) core excitations were detected. At low energies below 0.15 eV the recombination rate coefficient is dominated by strong 1s2(2s2p 3P)7l resonances with the strongest one occurring at an energy of only 21 meV. These resonances decisively influence the Mg IX recombination rate coefficient in a low temperature plasma. The experimentally derived Mg IX dielectronic recombination rate coefficient (±15% systematical uncertainty) is compared with the recommendation by Mazzotta et al. (1998, AandAS, 133, 403) and the recent calculations by Gu (2003, ApJ, 590, 1131) and by Colgan et al. (2003, AandA, 412, 597). These results deviate from the experimental rate coefficient by 130%, 82% and 25%, respectively, at the temperature where the fractional abundance of Mg IX is expected to peak in a photoionized plasma. At this temperature a theoretical uncertainty in the 1s2(2s2p 3P)7l resonance positions of only 100 meV would translate into an uncertainty of the plasma rate coefficient of almost a factor 3. This finding emphasizes that an accurate theoretical calculation of the Mg IX recombination rate coefficient from first principles is challenging. (authors)

  5. A molecular recombination map of Antirrhinum majus

    Directory of Open Access Journals (Sweden)

    Hudson Andrew

    2010-12-01

    Full Text Available Abstract Background Genetic recombination maps provide important frameworks for comparative genomics, identifying gene functions, assembling genome sequences and for breeding. The molecular recombination map currently available for the model eudicot Antirrhinum majus is the result of a cross with Antirrhinum molle, limiting its usefulness within A. majus. Results We created a molecular linkage map of A. majus based on segregation of markers in the F2 population of two inbred lab strains of A. majus. The resulting map consisted of over 300 markers in eight linkage groups, which could be aligned with a classical recombination map and the A. majus karyotype. The distribution of recombination frequencies and distorted transmission of parental alleles differed from those of a previous inter-species hybrid. The differences varied in magnitude and direction between chromosomes, suggesting that they had multiple causes. The map, which covered an estimated of 95% of the genome with an average interval of 2 cM, was used to analyze the distribution of a newly discovered family of MITE transposons and tested for its utility in positioning seven mutations that affect aspects of plant size. Conclusions The current map has an estimated interval of 1.28 Mb between markers. It shows a lower level of transmission ratio distortion and a longer length than the previous inter-species map, making it potentially more useful. The molecular recombination map further indicates that the IDLE MITE transposons are distributed throughout the genome and are relatively stable. The map proved effective in mapping classical morphological mutations of A. majus.

  6. Extrachromosomal recombination substrates recapitulate beyond 12/23 restricted VDJ recombination in nonlymphoid cells.

    Science.gov (United States)

    Jung, David; Bassing, Craig H; Fugmann, Sebastian D; Cheng, Hwei-Ling; Schatz, David G; Alt, Frederick W

    2003-01-01

    V(D)J recombination occurs efficiently only between gene segments flanked by recombination signals (RSs) containing 12 and 23 base pair spacers (the 12/23 rule). A further limitation "beyond the 12/23 rule" (B12/23) exists at the TCRbeta locus and ensures Dbeta usage. Herein, we show that extrachromosomal V(D)J recombination substrates recapitulate B12/23 restriction in nonlymphoid cells. We further demonstrate that the Vbeta coding flank, the 12-RS heptamer/nonamer, and the 23-RS spacer each can significantly influence B12/23 restriction. Finally, purified core RAG1 and RAG2 proteins (together with HMG2) also reproduce B12/23 restriction in a cell-free system. Our findings indicate that B12/23 restriction of V(D)J recombination is cemented at the level of interactions between the RAG proteins and TCRbeta RS sequences. PMID:12530976

  7. Regulation of homologous recombination at telomeres in budding yeast

    DEFF Research Database (Denmark)

    Eckert-Boulet, Nadine; Lisby, Michael

    2010-01-01

    Homologous recombination is suppressed at normal length telomere sequences. In contrast, telomere recombination is allowed when telomeres erode in the absence of telomerase activity or as a consequence of nucleolytic degradation or incomplete replication. Here, we review the mechanisms that...

  8. The Λ0 polarization and the recombination mechanism

    International Nuclear Information System (INIS)

    We use the recombination and the Thomas Precession Model to obtain a prediction for the Λ0 polarization in the p+p→Λ0+X reaction. We study the effect of the recombination function on the Λ0 polarization

  9. Branching innovation, recombinant innovation, and endogenous technological transitions

    NARCIS (Netherlands)

    Frenken, K.; Izquierdo, L.; Zeppini, P.

    2012-01-01

    We propose a model of technological transitions based on two different types of innovations. Branching innovations refer to technological improvements along a particular path, while recombinant innovations represent fusions of multiple paths. Recombinant innovations create "short-cuts" which reduce

  10. Production and characterization of recombinant lignin peroxidase isozyme H2 from Phanerochaete chrysosporium using recombinant baculovirus.

    Science.gov (United States)

    Johnson, T M; Pease, E A; Li, J K; Tien, M

    1992-08-01

    Recombinant Phanerochaete chrysosporium lignin peroxidase isozyme H2 (pI 4.4) was produced in insect cells infected with a genetically engineered baculovirus containing a copy of the cDNA clone lambda ML-6. The recombinant enzyme was purified to near homogeneity and is capable of oxidizing veratryl alcohol, iodide, and, to a lesser extent, guaiacol. The Km of the recombinant enzyme for veratryl alcohol and H2O2 is similar to that of the fungal enzyme. The guaiacol oxidation activity or any other activity is not dependent upon Mn2+. The purified recombinant peroxidase is glycosylated with N-linked carbohydrate(s). The recombinant lignin peroxidase eluted from an anion exchange resin similar to that of native isozyme H1 rather than H2. However, the pI of the recombinant enzymes is different from both H1 and H2 isozymes. Further characterization of native isozymes H1 and H2 from the fungal cultures revealed identical N-terminus residues. This indicates that isozymes H1 and H2 differ in post-translational modification. PMID:1632652

  11. Ion-ion recombination at high ion density

    International Nuclear Information System (INIS)

    By appeal to a Thomson-style treatment of recombination, it is shown that the rate for recombination of ions generated with uniform frequency within a reaction volume is a factor of 9/4 times greater than the rate for recombination of ions which approach each other from infinite separation. A valuable relationship connecting the two problems is uncovered. The analysis is pertinent to recombination involving dilute and high degrees of ionisation. (author)

  12. Hyper-Recombining Recipient Strains in Bacterial Conjugation

    OpenAIRE

    Feinstein, Sheldon I.; Low, K. Brooks

    1986-01-01

    Using a direct enrichment and screening procedure, mutants of Escherichia coli have been isolated in which recombination frequencies for several intragenic Hfr x F- crosses are significantly higher (twofold to sixfold) than in the parental strains. These hyper-recombination mutations comprised five new mutS- and one new mutL- allele. Together with other known mut - alleles, they were analyzed for effects on intragenic recombination using several types of crosses. Hyper-recombination was fou...

  13. Mechanism and control of interspecies recombination in Escherichia coli. I. Mismatch repair, methylation, recombination and replication functions.

    OpenAIRE

    Stambuk, S; Radman, M

    1998-01-01

    A genetic analysis of interspecies recombination in Escherichia coli between the linear Hfr DNA from Salmonella typhimurium and the circular recipient chromosome reveals some fundamental aspects of recombination between related DNA sequences. The MutS and MutL mismatch binding proteins edit (prevent) homeologous recombination between these 16% diverged genomes by at least two distinct mechanisms. One is MutH independent and presumably acts by aborting the initiated recombination through the U...

  14. Charge exchange recombination x-ray laser

    International Nuclear Information System (INIS)

    A recombining plasma x-ray laser using charge exchange recombination (CXR) is proposed. Fully stripped carbon ions collide with neutral He atoms and become excited hydrogenlike carbon ions, in which the excited levels with n=3 or 4 are mainly populated. We calculate the gain coefficients of the Balmer α and the Lyman β line of the hydrogenlike carbon ions by the use of a collisional-radiative model in which the CXR process is included. The calculated result shows that substantial gain can be generated for the Lyman β and Balmer α lines and that the gain of the Balmer α line can be strongly enhanced by the effect of CXR. We also report a preliminary experiment of this scheme. (author)

  15. Bacterial Artificial Chromosome Mutagenesis Using Recombineering

    Directory of Open Access Journals (Sweden)

    Kumaran Narayanan

    2011-01-01

    Full Text Available Gene expression from bacterial artificial chromosome (BAC clones has been demonstrated to facilitate physiologically relevant levels compared to viral and nonviral cDNA vectors. BACs are large enough to transfer intact genes in their native chromosomal setting together with flanking regulatory elements to provide all the signals for correct spatiotemporal gene expression. Until recently, the use of BACs for functional studies has been limited because their large size has inherently presented a major obstacle for introducing modifications using conventional genetic engineering strategies. The development of in vivo homologous recombination strategies based on recombineering in E. coli has helped resolve this problem by enabling facile engineering of high molecular weight BAC DNA without dependence on suitably placed restriction enzymes or cloning steps. These techniques have considerably expanded the possibilities for studying functional genetics using BACs in vitro and in vivo.

  16. Hα diagnostic in a recombining plasma

    Science.gov (United States)

    Wenzel, U.; Goto, M.

    2016-05-01

    In fusion devices the hydrogen Balmer lines are used to measure the neutral flux from the walls into the plasma using the atomic physics factor S/XB. This is a standard diagnostic which can be applied in ionizing plasma using {{H}α} , {{H}β} or {{H}γ} without knowledge of the electron density. We will extend this method to a recombining plasma in front of a surface. {{H}α} can be used in an analogous way to measure the plasma flow to this surface which can be e.g. a divertor target. The other Balmer lines are not suitable because the corresponding atomic physics factor R/YB depends on density due to three-body recombination. An application of this diagnostic method is provided.

  17. CFD Analysis of Passive Autocatalytic Recombiner

    Directory of Open Access Journals (Sweden)

    B. Gera

    2011-01-01

    Full Text Available In water-cooled nuclear power reactors, significant quantities of hydrogen could be produced following a postulated loss-of-coolant accident (LOCA along with nonavailability of emergency core cooling system (ECCS. Passive autocatalytic recombiners (PAR are implemented in the containment of water-cooled power reactors to mitigate the risk of hydrogen combustion. In the presence of hydrogen with available oxygen, a catalytic reaction occurs spontaneously at the catalyst surfaces below conventional ignition concentration limits and temperature and even in presence of steam. Heat of reaction produces natural convection flow through the enclosure and promotes mixing in the containment. For the assessment of the PAR performance in terms of maximum temperature of catalyst surface and outlet hydrogen concentration an in-house 3D CFD model has been developed. The code has been used to study the mechanism of catalytic recombination and has been tested for two literature-quoted experiments.

  18. Recombinant laccase: I. Enzyme cloning and characterization.

    Science.gov (United States)

    Nicolini, Claudio; Bruzzese, Debora; Cambria, Maria Teresa; Bragazzi, Nicola Luigi; Pechkova, Eugenia

    2013-03-01

    We obtained structural and functional characterization of a recombinant Laccase from Rigidoporus lignosus (formerly Rigidoporus microporus), a white-rot basidiomycete, by means of circular dichroism (CD) spectra, cyclic voltammetry (CV) and biochemical assays. Here we report the optimization of expression and purification procedures of a recombinant Laccase expressed in supercompetent Escherichia coli cells. We amplified the coding sequence of Laccase using PCR from cDNA and cloned into a bacterial expression system. The resulting expression plasmid, pET-28b, was under a strong T7/Lac promoter induced by IPTG (isopropyl-β-d-thiogalactoipyranoside). We obtained purification by fast protein liquid chromatography (FPLC) method. We recorded the variation of the current of a solution containing purified Laccase with increasing Syringaldazine (SGZ) concentration using a potentiometer as proof of principle, showing its compatibility with the development of a new enzymatic biosensor for medical purposes, as described in Part II. PMID:22991171

  19. Fibrinolytic Activity of Recombinant Mutant Streptokinase

    Directory of Open Access Journals (Sweden)

    Mahboobeh Mobarrez

    2015-04-01

    Full Text Available Background: Streptokinase is a bacterial protein produced by different beta hemolytic streptococci and widely used in thrombolytic treatment. The main disadvantage of using streptokinase is antibody formation which causes allergic reaction to neutralize effects of streptokinase therapy. Aim of this study was investigate of recombinant mutant streptokinase fibrinolytic activity.Materials and Methods: In this study recombinant mutant streptokinase without 42 amino acids from the C terminal region was purified by affinity S-Tag column chromatography and its fibrinolytic activity was studied.Results: The concentration of expressed and purified protein was 10 mg/ml. Its enzyme activity was assayed using zymography, radial caseinolytic activity and fibrin plate test methods and estimated quantitatively by casein digestion method compared to a commercial form.Conclusion: It was found that this product had the more volume and more enzymatic activity.

  20. Quark Recombination in Heavy Ion Collisions

    OpenAIRE

    Fries, Rainer J.(Cyclotron Institute, Department of Physics & Astronomy, Texas A&M University, College Station, TX, 77843-3366, USA)

    2011-01-01

    Data on high energy nuclear collisions collected at the Relativistic Heavy Ion Collider over the past decade have provided convincing evidence that hadronization is quite different in hot nuclear environments compared to p+p collisions. In particular, the data suggest that we see traces of quark degrees of freedom in elliptic flow, with the implication that collective flow is generated on the parton level and is transfered to hadrons through a simple recombination step. In this contribution w...

  1. Recombinant human erythropoietin in sports: a review

    OpenAIRE

    Rafael Maia de Almeida Bento; Lúcia Menezes Pinto Damasceno; Francisco Radler Aquino Neto

    2003-01-01

    Erythropoietin is an endogenous hormone of glicoproteic nature secreted by the kidneys and is the main regulator of the erythropoiesis. An alteration in its production generates a disturbance in the plasmatic concentration giving rise to several types of pathologies related to the hematopoietic system. The recombinant forms of erythropoietin have indiscriminately been used by athletes, mainly in endurance sports, by increasing the erythrocytes concentration, generating a better delivery of ox...

  2. Construction of recombinant DNA by exonuclease recession.

    OpenAIRE

    Yang, Y S; Watson, W J; Tucker, P W; Capra, J D

    1993-01-01

    We describe a new exonuclease-based method for joining and/or constructing two or more DNA molecules. DNA fragments containing ends complementary to those of a vector or another independent molecules were generated by the polymerase chain reaction. The 3' ends of these molecules as well as the vector DNA were then recessed by exonuclease activity and annealed in an orientation-determined manner via their complementary single-stranded regions. This recombinant DNA can be transformed directly i...

  3. Virus Strain Discrimination Using Recombinant Antibodies

    OpenAIRE

    Boonham, N.; Barker, I.

    2002-01-01

    Most routine testing for plant viruses is currently carried out using monoclonal and polyclonal antibodies. Traditional methods of antibody production however can be time consuming and require the use of expensive cell culture facilities. Recombinant antibody technology however is starting to make an impact in this area, enabling the selection of antibody fragments in a few weeks compared with the many months associated with traditional methods and requires only basic microbiological faciliti...

  4. Production of recombinant antibodies using bacteriophages

    OpenAIRE

    Shukra, A. M.; Sridevi, N. V.; Dev Chandran,; Kapil Maithal,

    2014-01-01

    Recombinant antibody fragments such as Fab, scFv, diabodies, triabodies, single domain antibodies and minibodies have recently emerged as potential alternatives to monoclonal antibodies, which can be engineered using phage display technology. These antibodies match the strengths of conventionally produced monoclonal antibodies and offer advantages for the development of immunodiagnostic kits and assays. These fragments not only retain the specificity of the whole monoclonal ...

  5. Recombination of vesicles during freeze-drying

    OpenAIRE

    Cabane, Bernard; Blanchon, Sylvène; Neves, Carole

    2006-01-01

    Concentrated dispersions of nanometric lipid vesicles (mean diameter 20 nm) in water/maltose solutions have been freeze-dried, and then redispersed in water, yielding again dispersions of lipid vesicles. At each stage of the freeze-drying process, the organization of the vesicles in the dispersion and their size distribution were examined through Small Angle Neutron Scattering and Gel Permeation Chromatography. It was found that the osmotic deswelling of the vesicles caused them to recombine ...

  6. Recombinant CBM-fusion technology : applications overview

    OpenAIRE

    Oliveira, Carla Cristina Marques de; Carvalho, Vera; Domingues, Lucília; Gama, F. M.

    2015-01-01

    Carbohydrate-binding modules (CBMs) are small components of several enzymes, which present an independent fold and function, and specific carbohydrate-binding activity. Their major function is to bind the enzyme to the substrate enhancing its catalytic activity, especially in the case of insoluble substrates. The immense diversity of CBMs, together with their unique properties, has long raised their attention for many biotechnological applications. Recombinant DNA technology has been used for...

  7. Asthma and Therapeutics: Recombinant Therapies in Asthma

    OpenAIRE

    Cockcroft Donald W

    2005-01-01

    Abstract Numerous recombinant therapies are being investigated for the treatment of asthma. This report reviews the current status of several of these novel agents. Anti-immunoglobulin (Ig)E (omalizumab, Xolair) markedly inhibits all aspects of the allergen challenge in subjects who have reduction of free serum IgE to undetectable levels. Several clinical studies in atopic asthma have demonstrated benefit by improved symptoms and lung function and a reduction in corticosteroid requirements. E...

  8. Modelling of procecces in catalytic recombiners

    International Nuclear Information System (INIS)

    In order to achieve a high degree of safety in nuclear power plants and prevent possible accident scenarios, their consequences are calculated and analysed with numeric codes. One of the most important part of nuclear safety research of hazardous incidents are development and validation of these numeric models, which are implemented into accident codes. The severe hydrogen release during a core meltdown is one of the considered scenario of performed accident analyses. One of the most important measure for the elimination of the hydrogen is catalytic recombiners. Converting the hydrogen with the atmospheric oxygen to water vapor in an exothermic reaction will prevent possible detonation of the hydrogen/air atmosphere. Within the dissertation the recombiner simulation REKO-DIREKT was developed and validated by an extensive experimental database. The performance of recombiners with regard to the conversion of the hydrogen and the temperature development is modelled. The REKO-DIREKT program is unique and has made significant revolution in research of hydrogen safety. For the first time it has been possible to show the performance of the recombiner so great in detail by using REKO-DIREKT. In the future engineers of nuclear power plants will have opportunity to have precise forecasts about the process of the possible accidents with hydrogen release. Also with presence of water vapor or with oxygen depletion which are included in the model. The major discussion of the hydrogen ignition at hot catalyst steel plates can be evaluated in the future with REKO-DIREKT more reliably than the existing used models. (orig.)

  9. Chi activity during transduction-associated recombination.

    OpenAIRE

    Dower, N. A.; Stahl, F. W.

    1981-01-01

    Chi is a genetic element that stimulates phage lambda recombination by the Escherichia coli recBC pathway during lytic infection [Stahl, F. W. (1979) Annu. Rev. Genet. 13, 7--24]. Herein we show that chi in lambda prophage influences exchange distribution in P1 phage-mediated transduction and in conjugation. This demonstration encourages the view that chi may influence genetic exchange in E. coli in the total absence of lambda.

  10. Determination of recombination in Mycoplasma hominis

    DEFF Research Database (Denmark)

    Jacobsen, Iben Søgaard; Boesen, Thomas; Mygind, Tina;

    2002-01-01

    Mycoplasma hominis has been previously described as a heterogeneous species, and in the present study intraspecies diversity of 20 M. hominis isolates from different individuals was analyzed using parts of the unlinked gyrase B (gyrB), elongation factor Tu (tuf), SRalpha homolog (ftsY), hit...... intergenic and intragenic recombination in M. hominis and this may explain the high intraspecies variability. The results obtained in the present study may be of importance for future population studies of Mycoplasma species....

  11. Dielectronic Recombination Rates In Astrophysical Plasmas

    CERN Document Server

    Bachari, F; Maero, G; Quarati, P; Bachari, Fatima; Ferro, Fabrizio; Maero, Giancarlo; Quarati, Piero

    2006-01-01

    In this work we introduce a new expression of the plasma Dielecronic Recombination (DR) rate as a function of the temperature, derived assuming a small deformation of the Maxwell-Boltzmann distribution and containing corrective factors, in addition to the usual exponential behaviour, caused by non-linear effects in slightly non ideal plasmas. We then compare the calculated DR rates with the experimental DR fits in the low temperature region.

  12. Recombination-assisted megaprimer (RAM) cloning

    OpenAIRE

    Jacques Mathieu; Emilia Alvarez; Alvarez, Pedro J. J.

    2014-01-01

    No molecular cloning technique is considered universally reliable, and many suffer from being too laborious, complex, or expensive. Restriction-free cloning is among the simplest, most rapid, and cost-effective methods, but does not always provide successful results. We modified this method to enhance its success rate through the use of exponential amplification coupled with homologous end-joining. This new method, recombination-assisted megaprimer (RAM) cloning, significantly extends the app...

  13. Development of Mycoplasma hyopneumoniae Recombinant Vaccines.

    Science.gov (United States)

    Marchioro, Silvana Beutinger; Simionatto, Simone; Dellagostin, Odir

    2016-01-01

    Mycoplasma hyopneumoniae is the etiological agent of swine enzootic pneumonia (EP), a disease that affects swine production worldwide. Vaccination is the most cost-effective strategy for the control and prevention of the disease. Research using genome-based approach has the potential to elucidate the biology and pathogenesis of M. hyopneumoniae and contribute to the development of more effective vaccines. Here, we describe the protocol for developing M. hyopneumoniae recombinant vaccines using reverse vaccinology approaches. PMID:27076288

  14. Mechanisms and factors that influence high frequency retroviral recombination

    DEFF Research Database (Denmark)

    Delviks-Frankenberry, Krista; Galli, Andrea; Nikolaitchik, Olga;

    2011-01-01

    With constantly changing environmental selection pressures, retroviruses rely upon recombination to reassort polymorphisms in their genomes and increase genetic diversity, which improves the chances for the survival of their population. Recombination occurs during DNA synthesis, whereby reverse...... of the recombination process, and evaluates the subsequent viral diversity and fitness of the progeny recombinant. Specifically, the high mutation rates and high recombination frequencies of HIV-1 will be analyzed for their roles in influencing HIV-1 global diversity, as well as HIV-1 diagnosis, drug treatment...

  15. Dissociative recombination of small molecular ions

    International Nuclear Information System (INIS)

    In this thesis an analysis is given of merged electron-ion beam experiment and work on dissociative recombination of molecular ions and electrons is described. Chapter II covers a brief introduction of the theory of dissociative recombination. In chapter III, a description is given of the merged electron-ion beam experiment and a method is described which allows the determination of the mean angle between the electron and ion trajectories in a merged electron-ion beam experiment. In chapter IV a paper on the three dominant atmospheric diatomic ions NO+, O2+ and N2+ is presented and in chapter V the dissociative recombination for N2H+ and N2D+ is discussed. In chapter VI two papers on the polyatomic ions of the carbon-containing molecular ions are presented, and in chapter VII a letter with some results of the work presented in more detail in the chapters IV, V and VI is presented. The magnitude and the energy dependence of the cross-section measured by the merged beam technique and by other techniques is compared and discussed. (Auth.)

  16. CFD modeling of passive autocatalytic recombiners*

    Directory of Open Access Journals (Sweden)

    Orszulik Magdalena

    2015-06-01

    Full Text Available This study deals with numerical modeling of passive autocatalytic hydrogen recombiners (PARs. Such devices are installed within containments of many nuclear reactors in order to remove hydrogen and convert it to steam. The main purpose of this work is to develop a numerical model of passive autocatalytic recombiner (PAR using the commercial computational fluid dynamics (CFD software ANSYS-FLUENT and tuning the model using experimental results. The REKO 3 experiment was used for this purpose. Experiment was made in the Institute for Safety Research and Reactor Technology in Julich (Germany. It has been performed for different hydrogen concentrations, different flow rates, the presence of steam, and different initial temperatures of the inlet mixture. The model of this experimental recombiner was elaborated within the framework of this work. The influence of mesh, gas thermal conductivity coefficient, mass diffusivity coefficients, and turbulence model was investigated. The best results with a good agreement with REKO 3 data were received for k-ɛ model of turbulence, gas thermal conductivity dependent on the temperature and mass diffusivity coefficients taken from CHEMKIN program. The validated model of the PAR was next implemented into simple two-dimensional simulations of hydrogen behavior within a subcompartment of a containment building.

  17. Antagonistic experimental coevolution with a parasite increases host recombination frequency

    Directory of Open Access Journals (Sweden)

    Kerstes Niels AG

    2012-02-01

    Full Text Available Abstract Background One of the big remaining challenges in evolutionary biology is to understand the evolution and maintenance of meiotic recombination. As recombination breaks down successful genotypes, it should be selected for only under very limited conditions. Yet, recombination is very common and phylogenetically widespread. The Red Queen Hypothesis is one of the most prominent hypotheses for the adaptive value of recombination and sexual reproduction. The Red Queen Hypothesis predicts an advantage of recombination for hosts that are coevolving with their parasites. We tested predictions of the hypothesis with experimental coevolution using the red flour beetle, Tribolium castaneum, and its microsporidian parasite, Nosema whitei. Results By measuring recombination directly in the individuals under selection, we found that recombination in the host population was increased after 11 generations of coevolution. Detailed insights into genotypic and phenotypic changes occurring during the coevolution experiment furthermore helped us to reconstruct the coevolutionary dynamics that were associated with this increase in recombination frequency. As coevolved lines maintained higher genetic diversity than control lines, and because there was no evidence for heterozygote advantage or for a plastic response of recombination to infection, the observed increase in recombination most likely represented an adaptive host response under Red Queen dynamics. Conclusions This study provides direct, experimental evidence for an increase in recombination frequency under host-parasite coevolution in an obligatory outcrossing species. Combined with earlier results, the Red Queen process is the most likely explanation for this observation.

  18. FASEB Summer Research Conference. Genetic Recombination and Chromosome Rearrangements

    Energy Technology Data Exchange (ETDEWEB)

    Jinks-Robertson, Sue

    2002-02-01

    The 2001 meeting entitled ''Genetic Recombination and Genome Rearrangements'' was held July 21-26 in Snowmass, Colorado. The goal of the meeting was to bring together scientists using diverse approaches to study all aspects of genetic recombination. This goal was achieved by integrating talks covering the genetics, biochemistry and structural biology of homologous recombination, site-specific recombination, and nonhomologous recombination. The format of the meeting consisted of a keynote address on the opening evening, two formal plenary sessions on each of the four full meeting days, a single afternoon workshop consisting of short talks chosen from among submitted abstracts, and afternoon poster sessions on each of the four full meeting days. The eight plenary session were entitled: (1) Recombination Mechanisms, (2) Prokaryotic Recombination, (3) Repair and Recombination, (4) Site-specific Recombination and Transposition, (5) Eukaryotic Recombination I, (6) Genome Rearrangements, (7) Meiosis, and (8) Eukaryotic Recombination II. Each session included a mix of genetic, biochemical and structural talks; talks were limited to 20 minutes, followed by 10 minutes of very lively, general discussion. Much of the data presented in the plenary sessions was unpublished, thus providing attendees with the most up-to-date knowledge of this rapidly-moving field.

  19. Monitoring homologous recombination in rice (Oryza sativa L.)

    International Nuclear Information System (INIS)

    Here we describe a system to assay homologous recombination during the complete life cycle of rice (Oryza sativa L.). Rice plants were transformed with two copies of non-functional GUS reporter overlap fragments as recombination substrate. Recombination was observed in all plant organs examined, from the seed stage until the flowering stage of somatic plant development. Embryogenic cells exhibited the highest recombination ability with an average of 3 x 10-5 recombination events per genome, which is about 10-fold of that observed in root cells, and two orders of that observed in leaf cells. Histological analysis revealed that recombination events occurred in diverse cell types, but preferentially in cells with small size. Examples of this included embryogenic cells in callus, phloem cells in the leaf vein, and cells located in the root apical meristem. Steady state RNA analysis revealed that the expression levels of rice Rad51 homologs are positively correlated with increased recombination rates in embryogenic calli, roots and anthers. Finally, radiation treatment of plantlets from distinct recombination lines increased the recombination frequency to different extents. These results showed that homologous recombination frequency can be effectively measured in rice using a transgene reporter assay. This system will facilitate the study of DNA damage signaling and homologous recombination in rice, a model monocot.

  20. Monitoring homologous recombination in rice (Oryza sativa L.)

    Energy Technology Data Exchange (ETDEWEB)

    Yang Zhuanying; Tang Li [Guangdong Provincial Key Lab of Biotechnology for Plant Development, College of Life Sciences, South China Normal University, Guangzhou 510631 (China); Li Meiru [South China Botanic Garden, Chinese Academy of Sciences, Guangzhou 510650 (China); Chen Lei; Xu Jie [Guangdong Provincial Key Lab of Biotechnology for Plant Development, College of Life Sciences, South China Normal University, Guangzhou 510631 (China); Wu Goujiang [South China Botanic Garden, Chinese Academy of Sciences, Guangzhou 510650 (China); Li Hongqing, E-mail: hqli@scnu.edu.cn [Guangdong Provincial Key Lab of Biotechnology for Plant Development, College of Life Sciences, South China Normal University, Guangzhou 510631 (China)

    2010-09-10

    Here we describe a system to assay homologous recombination during the complete life cycle of rice (Oryza sativa L.). Rice plants were transformed with two copies of non-functional GUS reporter overlap fragments as recombination substrate. Recombination was observed in all plant organs examined, from the seed stage until the flowering stage of somatic plant development. Embryogenic cells exhibited the highest recombination ability with an average of 3 x 10{sup -5} recombination events per genome, which is about 10-fold of that observed in root cells, and two orders of that observed in leaf cells. Histological analysis revealed that recombination events occurred in diverse cell types, but preferentially in cells with small size. Examples of this included embryogenic cells in callus, phloem cells in the leaf vein, and cells located in the root apical meristem. Steady state RNA analysis revealed that the expression levels of rice Rad51 homologs are positively correlated with increased recombination rates in embryogenic calli, roots and anthers. Finally, radiation treatment of plantlets from distinct recombination lines increased the recombination frequency to different extents. These results showed that homologous recombination frequency can be effectively measured in rice using a transgene reporter assay. This system will facilitate the study of DNA damage signaling and homologous recombination in rice, a model monocot.

  1. Molecular mechanisms of DNA recombination: testing mitotic and meiotic models

    International Nuclear Information System (INIS)

    A hyperhaploid n + 1 strain of Saccharomyces cerevisiae (LBL1) disomic for chromosome VII was employed to isolate hyper-rec and hypo-rec mutations affecting spontaneous mitotic gene conversion and intergenic recombination. The genotype of LBL1 permits simultaneous and independent identification of rec mutations that enhance or diminish gene conversion and those that enhance or diminish intergenic recombination. Five phenotypic groups of rec mutants were isolated following ultraviolet light mutagenesis. Rec mutations that simultaneously abolish or enhance both classes of recombinational events were detected. These results demonstrate that gene conversion and intergenic recombination are under joint genetic control in mitotic cells. Conversion-specific and intergenic recombination-specific rec mutants were also recovered. Their properties indicate that conversion and intergenic recombination are separable pheonomena dependent upon discrete REC genes. The rec mutants isolated in LBL1 provide a method to test molecular models of mitotic and meiotic recombination

  2. Recombinations to the Rydberg States of Hydrogen and Their Effect During the Cosmological Recombination Epoch

    CERN Document Server

    Chluba, J; Dursi, L J

    2010-01-01

    In this paper we discuss the effect of recombinations to highly excited states (n > 100) in hydrogen during the cosmological recombination epoch. For this purpose, we developed a new ODE solver for the recombination problem, based on an implicit Gear's method. This solver allows us to include up to 350 l-resolved shells or ~61 000 separate levels in the hydrogen model and to solve the recombination problem for one cosmology in ~27 hours. This is a huge improvement in performance over our previous recombination code, for which a 100-shell computation (5050 separate states) already required ~150 hours on a single processor. We show that for 350 shells down to redshift z ~200 the results for the free electron fraction have practically converged. The final modification in the free electron fraction at z ~200 decreases from about \\DeltaNe/Ne ~2.8% for 100 shells to \\DeltaNe/Ne ~1.6% for 350 shells. However, the associated changes in the CMB power spectra at large multipoles l are rather small, so that for accurate...

  3. Single-stranded heteroduplex intermediates in λ Red homologous recombination

    Directory of Open Access Journals (Sweden)

    Zhang Youming

    2010-07-01

    Full Text Available Abstract Background The Red proteins of lambda phage mediate probably the simplest and most efficient homologous recombination reactions yet described. However the mechanism of dsDNA recombination remains undefined. Results Here we show that the Red proteins can act via full length single stranded intermediates to establish single stranded heteroduplexes at the replication fork. We created asymmetrically digestible dsDNA substrates by exploiting the fact that Redα exonuclease activity requires a 5' phosphorylated end, or is blocked by phosphothioates. Using these substrates, we found that the most efficient configuration for dsDNA recombination occurred when the strand that can prime Okazaki-like synthesis contained both homology regions on the same ssDNA molecule. Furthermore, we show that Red recombination requires replication of the target molecule. Conclusions Hence we propose a new model for dsDNA recombination, termed 'beta' recombination, based on the formation of ssDNA heteroduplexes at the replication fork. Implications of the model were tested using (i an in situ assay for recombination, which showed that recombination generated mixed wild type and recombinant colonies; and (ii the predicted asymmetries of the homology arms, which showed that recombination is more sensitive to non-homologies attached to 5' than 3' ends. Whereas beta recombination can generate deletions in target BACs of at least 50 kb at about the same efficiency as small deletions, the converse event of insertion is very sensitive to increasing size. Insertions up to 3 kb are most efficiently achieved using beta recombination, however at greater sizes, an alternative Red-mediated mechanism(s appears to be equally efficient. These findings define a new intermediate in homologous recombination, which also has practical implications for recombineering with the Red proteins.

  4. The imperfect ancestral recombination graph reconstruction problem: upper bounds for recombination and homoplasy.

    Science.gov (United States)

    Lam, Fumei; Tarpine, Ryan; Istrail, Sorin

    2010-06-01

    One of the central problems in computational biology is the reconstruction of evolutionary histories. While models incorporating recombination and homoplasy have been studied separately, a missing component in the theory is a robust and flexible unifying model which incorporates both of these major biological events shaping genetic diversity. In this article, we introduce the first such unifying model and develop algorithms to find the optimal ancestral recombination graph incorporating recombinations and homoplasy events. The power of our framework is the connection between our formulation and the Directed Steiner Arborescence Problem in combinatorial optimization. We implement linear programming techniques as well as heuristics for the Directed Steiner Arborescence Problem, and use our methods to construct evolutionary histories for both simulated and real data sets. PMID:20583925

  5. Genetic recombination of ultraviolet-irradiated nonreplicating lambda DNA

    International Nuclear Information System (INIS)

    Genetic recombination of ultraviolet-irradiated, nonreplicating lambda DNA was studied. Escherichia coli homoimmune lysogens were infected with ultraviolet-irradiated lambda phage whose DNA possessed a tandem duplication of the A to V genes. Recombination between duplicated segments produced lambda, DNA molecules possessing only one copy of the A to V region. DNA was extracted from cells and used to transfect recombination-deficient spheroplasts. Transfection lysates were assayed for total lambda phage and recombinant (EDTA-resistant) phage. Ultraviolet-stimulated recombination was shown to be completely RecA-dependent, mostly RecF-dependent, and RecBC and RecE-independent. Experiments with excision repair-deficient (uvr-) bacteria suggested that ultraviolet-stimulated recombination occurred by both Uvr-dependent and Uvr-independent processes. A role for pyrimidine dimers in recombination was indicated by the reduction in recombination frequency subsequent to photoreactivation and by experiments using lambda phase irradiated under conditions that produce almost exclusively pyrimidine dimers. A role for photoproducts other than pyrimidine dimers was suggested by the photo-reactivation-insensitive component of 254nm-stimulated recombination and by the observation that recombination frequencies of 254-irradiated phage were much greater than those of 313 nm/acetophenone-irradiated phage when both types of phage possessed the same number of pyridimidine dimers per lambda duplex

  6. Live-Cell Imaging of Vaccinia Virus Recombination

    Science.gov (United States)

    Paszkowski, Patrick; Noyce, Ryan S.; Evans, David H.

    2016-01-01

    Recombination between co-infecting poxviruses provides an important mechanism for generating the genetic diversity that underpins evolution. However, poxviruses replicate in membrane-bound cytoplasmic structures known as factories or virosomes. These are enclosed structures that could impede DNA mixing between co-infecting viruses, and mixing would seem to be essential for this process. We hypothesize that virosome fusion events would be a prerequisite for recombination between co-infecting poxviruses, and this requirement could delay or limit viral recombination. We have engineered vaccinia virus (VACV) to express overlapping portions of mCherry fluorescent protein fused to a cro DNA-binding element. In cells also expressing an EGFP-cro fusion protein, this permits live tracking of virus DNA and genetic recombination using confocal microscopy. Our studies show that different types of recombination events exhibit different timing patterns, depending upon the relative locations of the recombining elements. Recombination between partly duplicated sequences is detected soon after post-replicative genes are expressed, as long as the reporter gene sequences are located in cis within an infecting genome. The same kinetics are also observed when the recombining elements are divided between VACV and transfected DNA. In contrast, recombination is delayed when the recombining sequences are located on different co-infecting viruses, and mature recombinants aren’t detected until well after late gene expression is well established. The delay supports the hypothesis that factories impede inter-viral recombination, but even after factories merge there remain further constraints limiting virus DNA mixing and recombinant gene assembly. This delay could be related to the continued presence of ER-derived membranes within the fused virosomes, membranes that may once have wrapped individual factories. PMID:27525721

  7. Mode and recombination control in semiconductor lasers

    International Nuclear Information System (INIS)

    A self consistent mathematical description of a semiconductor GaAlAs heterostructure laser has been developed. It includes excess hole and electron injection, diffusion, drift and recombination. The excess carrier motion is described by the ambipolar diffusion equation. The boundary conditions at each heterojunction are found by imposing electron and hole current continuity as well as quasi-Fermi level continuity. The Fermi-level continuity condition is applied using Kane's non-parabolicity for the GAMMA1/sub C/ minimum and a parabolic expression for both the GAMMA15 /sub v/ and the X1/sub C/ minima. The effect of aluminum concentration on carrier mobility, effective mass and gap is included. The volume recombination rate is related to the optical gain of the laser in linear fashion using coefficients obtained by integrating over parabolic bands without quasi-momentum conservation. The recombination lifetime is found in a similar manner. The diffusion coefficients are calculated using the generalized Einstein equation. The dependence of the index of refraction in the device upon carrier injection is included. The E-M field is calculated by solving Maxwell's equations for a general five layer dielectric waveguide. Above threshold the gain is assumed to be pinned at the threshold value. For each solution, the E--M field distribution is determined self-consistently for a particular excess carrier distribution. The theory has been applied extensively to many contemporary laser structures, including double heterostructure, single heterostructure and symmetrical optical cavities. Design curves including injection efficiencies, peak power at catastrophic degradation, threshold current density and I--V characteristics have been developed for various cavity geometries and dopants

  8. Functions and structures of eukaryotic recombination proteins

    International Nuclear Information System (INIS)

    We have found that Rad51 and RecA Proteins form strikingly similar structures together with dsDNA and ATP. Their right handed helical nucleoprotein filaments extend the B-form DNA double helixes to 1.5 times in length and wind the helix. The similarity and uniqueness of their structures must reflect functional homologies between these proteins. Therefore, it is highly probable that similar recombination proteins are present in various organisms of different evolutional states. We have succeeded to clone RAD51 genes from human, mouse, chicken and fission yeast genes, and found that the homologues are widely distributed in eukaryotes. The HsRad51 and MmRad51 or ChRad51 proteins consist of 339 amino acids differing only by 4 or 12 amino acids, respectively, and highly homologous to both yeast proteins, but less so to Dmcl. All of these proteins are homologous to the region from residues 33 to 240 of RecA which was named ''homologous core. The homologous core is likely to be responsible for functions common for all of them, such as the formation of helical nucleoprotein filament that is considered to be involved in homologous pairing in the recombination reaction. The mouse gene is transcribed at a high level in thymus, spleen, testis, and ovary, at lower level in brain and at a further lower level in some other tissues. It is transcribed efficiently in recombination active tissues. A clear functional difference of Rad51 homologues from RecA was suggested by the failure of heterologous genes to complement the deficiency of Scrad51 mutants. This failure seems to reflect the absence of a compatible partner, such as ScRad52 protein in the case of ScRad51 protein, between different species. Thus, these discoveries play a role of the starting point to understand the fundamental gene targeting in mammalian cells and in gene therapy. (J.P.N.)

  9. Xylose utilizing recombinant Saccharomyces cerevisiae strains

    Energy Technology Data Exchange (ETDEWEB)

    Walfridsson, M.

    1996-04-01

    Through metabolic engineering, S. cerevisiae was provided with the necessary enzymes required for xylose utilisation during ethanolic fermentation of xylose-rich lignocellulose raw materials. For xylitol production, S. cerevisiae was provided with the Pichia stipitis XYL1 gene encoding xylose reductase (XR). The in-vivo reduction and the following excretion of xylitol, requires a co-substrate for maintenance and cofactor regeneration. Xylitol yields close to 100% were obtained with the XYL1 containing S. cerevisiae. Introducing P. stipitis XYL1 and XYL2 genes, encoding XR and xylitol dehydrogenase (XDH), respectively, enabled S. cerevisiae to convert xylose to xylulose, via xylitol. During the screening work of P. stipitis XDH gene, another gene encoding a polyol dehydrogenase was isolated and cloned in S. cerevisiae. The gene was identified as a D-arabinitol dehydrogenase gene. In P. stipitis it may function as a redox sink by reducing D-ribulose to D-arabinitol. The metabolism through the pentose phosphate pathway (PPP) was enhanced by over-expressing the native genes TKL1 and TAL1 encoding transketolase and transaldolase, respectively, resulting in improved xylose utilisation. The XR and XDH activities in recombinant S. cerevisiae were produced at different levels by constructing yeast vectors in which the PGK1 and ADHI promoters controlled XYL1 and XYL2. With higher XDH than XR activities, less by-products, in the form of xylitol and glycerol, were formed by the recombinant S. cerevisiae strains. The Thermus thermophilus xylA gene encoding a thermostable xylose isomerase was cloned and expressed in S. cerevisiae. The recombinant xylose isomerase was actively produced and a new functional metabolic pathway was established in S. cerevisiae resulting in ethanol production from xylose. 150 refs, 3 figs, 4 tabs

  10. Recombination Reactions and Commissioning of DESIREE

    International Nuclear Information System (INIS)

    By combining electron scattering calculations with structure calculations molecular potential energy curves, couplings and autoionization widths are obtained. Using this molecular data the cross sections of different recombination reactions relevant for the fusion plasma of the Divertor can be calculated. Here electron-molecular ion collisions leading to either dissociative recombination, vibrational excitation (or de-excitation) or dissociative excitation have been studied. Furthermore, the believed presence of H- in the plasma is a motivation for the study of mutual neutralization in collisions between H- and light atomic cations (H+, He+, Be+). We have performed both quantum ab initio as well as semi-classical calculations on reactions involving the H2, HeH and BeH molecular systems. On H2, the focus has been on the mutual neutralization reaction in collisions of H+ and H. An fully quantum ab initio study of the reaction produce total cross section and final state distributions in good agreement with experimental studies. Additionally, the neutralization cross sections are computed for collisions between different isotopes of the hydrogen ions and a very small isotope effects are observed. Furthermore, the differential cross section of the reaction is calculated. A semi- classical Landau-Zener model is used to study the reaction. Different methods to obtain the electronic coupling elements between ionic and covalent states are examined by comparing the semiclassical results with those obtained quantum mechanically. Theoretical studies of dissociative excitation of HeH+ are performed where both the resonant and direct processes are investigated. Calculations on the non-adiabatic couplings between resonant states of HeH are under the way and goal is to perform a fully quantum ab intio study of mutual neutralization in He++H- collisions as well dissociative recombination and resonant ion-pair formation. The direct mechanism of dissociative recombination of BeH+ has

  11. Hydrogen recombiner catalyst test supporting data

    Energy Technology Data Exchange (ETDEWEB)

    Britton, M.D.

    1995-01-19

    This is a data package supporting the Hydrogen Recombiner Catalyst Performance and Carbon Monoxide Sorption Capacity Test Report, WHC-SD-WM-TRP-211, Rev 0. This report contains 10 appendices which consist of the following: Mass spectrometer analysis reports: HRC samples 93-001 through 93-157; Gas spectrometry analysis reports: HRC samples 93-141 through 93-658; Mass spectrometer procedure PNL-MA-299 ALO-284; Alternate analytical method for ammonia and water vapor; Sample log sheets; Job Safety analysis; Certificate of mixture analysis for feed gases; Flow controller calibration check; Westinghouse Standards Laboratory report on Bois flow calibrator; and Sorption capacity test data, tables, and graphs.

  12. Hydrogen recombiner catalyst test supporting data

    International Nuclear Information System (INIS)

    This is a data package supporting the Hydrogen Recombiner Catalyst Performance and Carbon Monoxide Sorption Capacity Test Report, WHC-SD-WM-TRP-211, Rev 0. This report contains 10 appendices which consist of the following: Mass spectrometer analysis reports: HRC samples 93-001 through 93-157; Gas spectrometry analysis reports: HRC samples 93-141 through 93-658; Mass spectrometer procedure PNL-MA-299 ALO-284; Alternate analytical method for ammonia and water vapor; Sample log sheets; Job Safety analysis; Certificate of mixture analysis for feed gases; Flow controller calibration check; Westinghouse Standards Laboratory report on Bois flow calibrator; and Sorption capacity test data, tables, and graphs

  13. Cutaneous allergy to human (recombinant DNA) insulin.

    Science.gov (United States)

    Grammer, L C; Metzger, B E; Patterson, R

    1984-03-16

    p6 report two cases of cutaneous allergy to human (recombinant DNA) insulin. Each patient had a history of systemic allergic reactions to porcine insulin and was at least as reactive to human as to porcine insulin by end-point cutaneous titration. Both patients' insulin allergy was managed with animal insulins and both have done well. Our experience with these two patients indicates that human insulin (rDNA) should not be expected to be efficacious in all patients with systemic allergy to insulin. PMID:6366262

  14. Regulation of Homologous Recombination by SUMOylation

    DEFF Research Database (Denmark)

    Pinela da Silva, Sonia Cristina

    , deletions, and genome rearrangements that can lead to cell death or cancer in humans. The post-translational modification by SUMO (small ubiquitinlike modifier) has proven to be an important regulator of HR and genome integrity, but the molecular mechanisms responsible for these roles are still unclear. In...... this study I present new insights for the role of SUMOylation in regulating HR by dissecting the role of SUMO in the interaction between the central HR-mediator protein Rad52 and its paralogue Rad59 and the outcome of recombination. This data provides evidence for the importance of SUMO in promoting...

  15. Engineering thermoacidophilic archaea using linear DNA recombination.

    Science.gov (United States)

    Maezato, Yukari; Dana, Karl; Blum, Paul

    2011-01-01

    Thermoacidophilic archaea comprise one of the major classes of extremophiles. Most belong to the family Sulfolobales within the phylum Crenarchaeota. They are of applied interest as sources of hyperstable enzymes, for biomining of base and precious metals, and for evolutionary studies because of their use of eukaryotic-like subcellular mechanisms. Genetic methods are available for several species particularly Sulfolobus solfataricus. This organism has a considerable number of methods available for the construction of novel cell lines with unique functions. This chapter presents recent developments in the use of homologous recombination and linear DNA for the engineering of site-specific changes in the genome of S. solfataricus. PMID:21815108

  16. The landscape of recombination in African Americans

    OpenAIRE

    Anjali G Hinch; Tandon, Arti; Patterson, Nick; Song, Yunli; Rohland, Nadin; Palmer, Cameron D; Chen, Gary K.; Wang, Kai; Buxbaum, Sarah G.; Akylbekova, Meggie; Aldrich, Melinda C.; Ambrosone, Christine B.; Amos, Christopher; Bandera, Elisa V.; Berndt, Sonja I.

    2011-01-01

    Recombination, together with mutation, is the ultimate source of genetic variation in populations. We leverage the recent mixture of people of African and European ancestry in the Americas to build a genetic map measuring the probability of crossing-over at each position in the genome, based on about 2.1 million crossovers in 30,000 unrelated African Americans. At intervals of more than three megabases it is nearly identical to a map built in Europeans. At finer scales it differs significantl...

  17. Induction of intrachromosomal homologous recombination in whole plants

    International Nuclear Information System (INIS)

    The influence of different factors on frequencies of intrachromosomal homologous recombination in whole Arabidopsis thaliana and tobacco plants was analyzed using a disrupted β-glucuronidase marker gene. Recombination frequencies were enhanced several fold by DNA damaging agents like UV-light or MMS (methyl methanesulfonate). Applying 3-methoxybenzamide (3-MB), an inhibitor of poly(ADP)ribose polymerase (PARP), an enzyme that is postulated to be involved in DNA repair, enhanced homologous recombination frequencies strongly. These findings indicate that homologous recombination is involved in DNA repair and can (at least partially) compensate for other DNA repair pathways. Indications that recombination in plants can be induced by environmental stress factors that are not likely to be involved in DNA metabolism were also found; Arabidopsis plants growing in a medium containing 0.1 M NaCl exhibited elevated recombination frequencies. The possible general effects of ‘environmental’ challenges on genome flexibility are discussed. (author)

  18. IV. Dissociative recombination of electrons and molecular ions

    International Nuclear Information System (INIS)

    The present state of the theory of the dissociative recombination of electrons and molecular ions is reviewed and its shortcomings shown. The mechanisms of direct and indirect dissociative processes are described. Several approximative methods employing the analogy with the recombination of atomic ions and electrons are used for the determination of the dissociative recombination factor. Analyzing the derived formulae the temperature dependence of the dissociative recombination factor is determined and the results are compared with experimental data obtained by several authors. The energy levels of atoms created at the dissociative recombination of He2+, Ar2+, and O2+ ions are described. Methods of measuring the recombination factor are listed. The existing experimental data are summarized and the possible explanation of the observed variations is presented. An exhaustive list of references is given. (J.U.)

  19. Homologous recombination-mediated cloning and manipulation of genomic DNA regions using Gateway and recombineering systems

    Directory of Open Access Journals (Sweden)

    Kagale Sateesh

    2008-11-01

    Full Text Available Abstract Background Employing genomic DNA clones to characterise gene attributes has several advantages over the use of cDNA clones, including the presence of native transcription and translation regulatory sequences as well as a representation of the complete repertoire of potential splice variants encoded by the gene. However, working with genomic DNA clones has traditionally been tedious due to their large size relative to cDNA clones and the presence, absence or position of particular restriction enzyme sites that may complicate conventional in vitro cloning procedures. Results To enable efficient cloning and manipulation of genomic DNA fragments for the purposes of gene expression and reporter-gene studies we have combined aspects of the Gateway system and a bacteriophage-based homologous recombination (i.e. recombineering system. To apply the method for characterising plant genes we developed novel Gateway and plant transformation vectors that are of small size and incorporate selectable markers which enable efficient identification of recombinant clones. We demonstrate that the genomic coding region of a gene can be directly cloned into a Gateway Entry vector by recombineering enabling its subsequent transfer to Gateway Expression vectors. We also demonstrate how the coding and regulatory regions of a gene can be directly cloned into a plant transformation vector by recombineering. This construct was then rapidly converted into a novel Gateway Expression vector incorporating cognate 5' and 3' regulatory regions by using recombineering to replace the intervening coding region with the Gateway Destination cassette. Such expression vectors can be applied to characterise gene regulatory regions through development of reporter-gene fusions, using the Gateway Entry clones of GUS and GFP described here, or for ectopic expression of a coding region cloned into a Gateway Entry vector. We exemplify the utility of this approach with the Arabidopsis

  20. ACG: rapid inference of population history from recombining nucleotide sequences

    OpenAIRE

    O'Fallon Brendan D

    2013-01-01

    Abstract Background Reconstruction of population history from genetic data often requires Monte Carlo integration over the genealogy of the samples. Among tools that perform such computations, few are able to consider genetic histories including recombination events, precluding their use on most alignments of nuclear DNA. Explicit consideration of recombinations requires modeling the history of the sequences with an Ancestral Recombination Graph (ARG) in place of a simple tree, which presents...

  1. Development of Recombinant Cationic Polymers for Gene Therapy Research

    OpenAIRE

    Canine, Brenda F.; Hatefi, Arash

    2010-01-01

    Cationic polymers created through recombinant DNA technology have the potential to fill a void in the area of gene delivery. The recombinant cationic polymers to be discussed here are amino acid based polymers synthesized in E.coli with the purpose to not only address the major barriers to efficient gene delivery but offer safety, biodegradability, targetability and cost-effectiveness. This review helps the readers to get a better understanding about the evolution of recombinant cationic poly...

  2. Direct demonstration of retroviral recombination in a rhesus monkey.

    OpenAIRE

    Wooley, D P; Smith, R A; Czajak, S; Desrosiers, R C

    1997-01-01

    Recombination may be an important mechanism for increasing variation in retroviral populations. Retroviral recombination has been demonstrated in tissue culture systems by artificially creating doubly infected cells. Evidence for retroviral recombination in vivo is indirect and is based principally on the identification of apparently mosaic human immunodeficiency virus type 1 genomes from phylogenetic analyses of viral sequences. We infected a rhesus monkey with two different molecularly clon...

  3. On the evolutionary advantage of fitness-associated recombination.

    OpenAIRE

    Hadany, Lilach; Beker, Tuvik

    2003-01-01

    The adaptive value of recombination remains something of a puzzle. One of the basic problems is that recombination not only creates new and advantageous genetic combinations, but also breaks down existing good ones. A negative correlation between the fitness of an individual and its recombination rate would result in prolonged integrity of fitter genetic combinations while enabling less fit ones to produce new combinations. Such a correlation could be mediated by various factors, including st...

  4. Reconstructing the modular recombination history of Staphylococcus aureus phages

    OpenAIRE

    Swenson, Krister M; Guertin, Paul; Deschênes, Hugo; Bergeron, Anne

    2013-01-01

    Background Viruses that infect bacteria, called phages, are well-known for their extreme mosaicism, in which an individual genome shares many different parts with many others. The mechanisms for creating these mosaics are largely unknown but are believed to be recombinations, either illegitimate, or partly homologous. In order to reconstruct the history of these recombinations, we need to identify the positions where recombinations may have occurred, and develop algorithms to generate and exp...

  5. Dissociative recombination of N2H+

    Science.gov (United States)

    dos Santos, S. Fonseca; Ngassam, V.; Orel, A. E.; Larson, Å.

    2016-08-01

    The direct and indirect mechanisms of dissociative recombination of N2H+ are theoretically studied. At low energies, the electron capture is found to be driven by recombination into bound Rydberg states, while at collision energies above 0.1 eV, the direct capture and dissociation along electronic resonant states becomes important. Electron-scattering calculations using the complex Kohn variational method are performed to obtain the scattering matrix as well as energy positions and autoionization widths of resonant states. Potential-energy surfaces of electronic bound states of N2H and N2H+ are computed using structure calculations with the multireference configuration interaction method. The cross section for the indirect mechanism is calculated using a vibrational frame transformation of the elements of the scattering matrix at energies just above the ionization threshold. Here vibrational excitations of the ionic core from v =0 to v =1 and v =2 for all three normal modes are considered and autoionization is neglected. The cross section for the direct dissociation along electronic resonant states is computed with wave-packet calculations using the multiconfiguration time-dependent Hartree method, where all three internal degrees of freedom are considered. The calculated cross sections are compared to measurements.

  6. [Telomere Recombination in Normal Mammalian Cells].

    Science.gov (United States)

    Zhdanova, N S; Rubtsov, N B

    2016-01-01

    Two mechanisms of telomere length maintenance are known to date. The first includes the use of a special enzymatic telomerase complex to solve the problems that arise during the replication of linear DNA in a normal diploid and part of tumor cells. Alternative lengthening of telomeres (ALT), which is based on the homologous recombination of telomere DNA, represents the second mechanism. Until recently, ALT was assumed to be expressed only in 15-20% of tumors lacking active telomerase and, together with telomerase reactivation represented one of two possibilities to overcome the replicative senescence observed in somatic mammalian cells due to aging or during cell culturing in vitro. Previously described sporadic cases of combinations of the two mechanisms of telomere length maintenance in several cell lines in vitro were attributed to the experimental design rather than to a real biological phenomenon, since active cellular division without active telomerase was considered to be the "gold standard" of ALT. The present review describes the morphological and functional reorganizations of mammalian telomeres observed with ALT activation, as well as recently observed,and well-documented cases of combinations between ALT-like and telomerase-dependent mechanisms in mammalian cells. The possible role of telomere recombination in telomerase-dependent cells is discussed. PMID:27183789

  7. Recombinant shark natural antibodies to thyroglobulin.

    Science.gov (United States)

    Schluter, Samuel F; Jensen, Ingvill; Ramsland, Paul A; Marchalonis, John J

    2005-01-01

    As cartilaginous fish are the vertebrates most distal from man to produce antibodies, fundamental information regarding conservation and variation of the antigen binding site should be gained by comparing the properties of antibodies directed against the same antigen from the two species. Since monoclonal cell lines cannot be generated using shark B cells, we isolated antigen binding recombinant single chain Fv antibodies (scFv) comprising of the complete variable regions from shark light and heavy chains. Thyroglobulin was used as the selecting antigen as both sharks and humans express natural antibodies to mammalian thyroglobulin in the absence of purposeful immunization. We report that recombinant sandbar shark (Carcharhinus plumbeus) scFvs that bind bovine thyroglobulin consist of heavy chain variable regions (VH) homologous to those of the human VHIII subset and light chain variable regions (VL) homologous to those of the human Vlambda6 subgroup. The homology within the frameworks is sufficient to enable the building of three-dimensional models of the shark VH/VL structure using established human structures as templates. In natural antibodies of both species, the major variability lies in the third complementarity determining region (CDR3) of both VH and VL. PMID:15954089

  8. H2 recombination on interstellar grains

    International Nuclear Information System (INIS)

    From a consideration of relevant theoretical and experimental data it is concluded that H atoms (but not H2 molecules) will be chemisorbed on interstellar graphite grains, with H2 formation proceeding efficiently for graphite grain temperatures less than 70 K. It is argued that graphite grains will act as the principle sites for H2 formation, with a formation rate of Rapprox. =4 x 10/sup -17/ cm3 s/sup -1/. Heating by H2 molecules formed by surface recombination is analyzed in the context of the available experimental data, and a heating rate is derived and compared with other suggested cloud heating mechanisms. We conclude that H2 recombination will provide the largest heat source in diffuse clouds if the albedo of interstellar dust in the 912--1200 A region is high (approx.0.9), whereas if the albedo in this wavelength region is lower (approx.0.5), photoelectron ejection from grains will tend to predominate, and can explain observed cloud temperatures with a carbon depletion factor of approximately 2, a factor attributable to a normal interstellar abundance of graphite grains

  9. Numerical and experimental investigations on catalytic recombiners

    International Nuclear Information System (INIS)

    Numerous containments of European light water reactors (LWR) are equipped with passive auto-catalytic recombiners (PAR). These devices are designed for the removal of hydrogen generated during a severe accident in order to avoid serious damage caused by a detonation. PARs make use of the fact that hydrogen and oxygen react exothermally on catalytic surfaces generating steam and heat even below conventional ignition concentrations and temperatures. Activities at ISR aim at overcoming existing limitations of today's systems. These are e.g. limited conversion capacity or unintended ignition of the gaseous mixture due to overheating of the catalyst elements caused by strong reaction heat generation. Experiments at the REKO facilities are conducted in order to achieve a profound understanding of the processes inside a recombiner, such as reaction kinetics or heat and mass transfer. Innovative PAR designs which may overcome existing limitations can be developed based on the knowledge obtained from these experiments. For the analysis of the processes inside a PAR the numerical code REKO-DIREKT is being developed. The code calculates the local catalyst temperatures and the concentration regression along the catalyst plates. For the validation of the model numerous experiments have been performed with different types of coating and different plate arrangements. The first calculations fit well with the experimental results indicating a proper understanding of the fundamental processes. The paper describes the experiments as well as the numerical model and presents model calculations in comparison with experimental results. (authors)

  10. Homologous recombination: from model organisms to human disease

    NARCIS (Netherlands)

    M. Modesti (Mauro); R. Kanaar (Roland)

    2001-01-01

    textabstractRecent experiments show that properly controlled recombination between homologous DNA molecules is essential for the maintenance of genome stability and for the prevention of tumorigenesis.

  11. Ion-pair formation in electron recombination with molecular ions

    International Nuclear Information System (INIS)

    By studying ion-pair formation in electron recombination with molecular ions, fundamental knowledge on the molecular dynamics can be obtained. In order to study these types of reactions, both the electron recombination as well as the dynamics all the way to the asymptotic limits must be well described. We have used the wave packet technique to study ion-pair formation in electron recombination with HeH+, HD+, H3+ and HF+. We here discuss what will determine the general shape of the ion-pair cross section, the threshold effects, possible interference effects as well as the ratio of the cross sections of ion-pair formation to dissociative recombination

  12. Photoionization and electron-ion recombination of Ti I

    Science.gov (United States)

    Nahar, Sultana N.

    2016-07-01

    Study of the inverse processes of photoionization and electron-ion recombination of (Ti I + h ν ⇋ Ti II + e) using the unified method is reported. The method, based on close coupling (CC) approximation and R-matrix method, subsumes both the radiative recombination (RR) and dielectronic recombination (DR) in a unified manner and provides state-specific and total electron-ion recombination rate coefficients which are self-consistent with the state-specific photoionization cross sections. The present results include state-specific electron-ion recombination rates (αRC(i))and partial photoionization cross sections (σPI(i)) leaving the ion in the ground state of 813 bound states with n ≤ 10 and l ≤ 9 of Ti I. Various features of state-specific and total electron-ion recombination with temperature, and the corresponding photoionization cross sections with energies are discussed with illustrations. Due to closely lying excited states near the ground state of the core, photoionization cross sections show presence of narrow Rydberg resonances in low energy region near the ionization threshold. Many excited states also show broad and enhanced Seaton resonances due to PEC (photo-excitation-of-core) which contribute to the high temperature recombination. The total recombination rate coefficient is found to show a low hump around temperature 280 K and a high dielectronic recombination peak at temperature 25,000 K. Total spectrum of recombination cross sections and rates with photoelectron energy are also presented for experimental observation. Calculations were carried out using a CC wave function expansion of 36 states of the core ion Ti II. The large set of data for recombination rates and partial photoionization cross sections with resonances should provide a complete and accurate modelings of plasmas.

  13. Time evolution of an irreversible recombination process

    International Nuclear Information System (INIS)

    The time evolution of the irreversible catalytic recombination process, A + B → inert is studied both analytically as well as by computer simulation. A rate equation describing this process is derived. For situations where one of the species poisons the catalyst, the minority species, under certain conditions, is found to decay exponentially. Computer simulation results also indicate exponential decay for intermediate times. Near the poisoning transition, xA ≅ xB, the average relaxation time is found to diverge as τ ∼ (1)/(0.5-xA)γ with γ ≅ 1.3. Here xA and xB are the compositions of A and B in the gas. (author). 6 refs, 4 figs

  14. Epidemiology, Genetic Recombination, and Pathogenesis of Coronaviruses.

    Science.gov (United States)

    Su, Shuo; Wong, Gary; Shi, Weifeng; Liu, Jun; Lai, Alexander C K; Zhou, Jiyong; Liu, Wenjun; Bi, Yuhai; Gao, George F

    2016-06-01

    Human coronaviruses (HCoVs) were first described in the 1960s for patients with the common cold. Since then, more HCoVs have been discovered, including those that cause severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), two pathogens that, upon infection, can cause fatal respiratory disease in humans. It was recently discovered that dromedary camels in Saudi Arabia harbor three different HCoV species, including a dominant MERS HCoV lineage that was responsible for the outbreaks in the Middle East and South Korea during 2015. In this review we aim to compare and contrast the different HCoVs with regard to epidemiology and pathogenesis, in addition to the virus evolution and recombination events which have, on occasion, resulted in outbreaks amongst humans. PMID:27012512

  15. Initiation of Meiotic Recombination in Mammals

    Directory of Open Access Journals (Sweden)

    Rajeev Kumar

    2010-12-01

    Full Text Available Meiotic recombination is initiated by the induction of programmed DNA double strand breaks (DSBs. DSB repair promotes homologous interactions and pairing and leads to the formation of crossovers (COs, which are required for the proper reductional segregation at the first meiotic division. In mammals, several hundred DSBs are generated at the beginning of meiotic prophase by the catalytic activity of SPO11. Currently it is not well understood how the frequency and timing of DSB formation and their localization are regulated. Several approaches in humans and mice have provided an extensive description of the localization of initiation events based on CO mapping, leading to the identification and characterization of preferred sites (hotspots of initiation. This review presents the current knowledge about the proteins known to be involved in this process, the sites where initiation takes place, and the factors that control hotspot localization.

  16. Recombinant Brucella abortus gene expressing immunogenic protein

    Energy Technology Data Exchange (ETDEWEB)

    Mayfield, J.E.; Tabatabai, L.B.

    1991-06-11

    This patent describes a synthetic recombinant DNA molecule containing a DNA sequence. It comprises a gene of Brucella abortus encoding an immunogenic protein having a molecular weight of approximately 31,000 daltons as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis under denaturing conditions, the protein having an isoelectric point around 4.9, and containing a twenty-five amino acid sequence from its amino terminal end consisting of Gln-Ala-Pro-Thr-Phe-Phe-Arg-Ile-Gly-Thr-Gly-Gly-Thr-Ala-Gly-Thr-Tyr-Tyr-Pro-Ile-Gly-Gly-Leu-Ile-Ala, wherein Gln, Ala, Pro, Thr, Phe, Arg, Ile, Gly, Tyr, and Leu, respectively, represent glutamine, alanine, proline, threonine, phenylalanine, arginine, isolecuine, glycine, tyrosine, and leucine.

  17. Radio recombination lines from H II regions

    International Nuclear Information System (INIS)

    Radio recombination lines have been observed from forty-six H II regions. The Arecibo 1000-foot radio telescope was used to provide high sensitivity and high angular resolution at 1400 MHz (gain approx. 7.70K/Jy, HPBW = 3:2) and 2372 MHZ (gain approx. 6.30K/Jy, HPBW = 2'). Observations were made at 1400 MHz in the frequency switching mode, and at 2372 MHz in the total power mode. Gaussians were fit to be observed lines to derive velocities, line widths, and line temperatures. From the velocities kinematic distances were derived. For eleven sources H I absorption measurements were also made. The absorption spectra enabled the kinematic distance ambiguity to be resolved for some sources. The absorption spectra themselves were found to have extremely sharp, non-gaussian edges. One explanation for these is a model where the interstellar medium contains many H I cloudlets with T/sub s/less than or equal to 1000K and turbulent velocities less than or equal to 3 km/s. The H I absorption spectrum is then a superposition of many narrow gaussian profiles. It was also found from a comparison of H I absorption velocities with radio recombination line velocities that peculiar motions exist in the interstellar medium with velocities of up to 10 km/s. Using the measured line temperatures and continuum temperatures, estimates were desired of emission measures, electron temperatures, and electron densities, using a non-LTE analysis. Non-LTE effects were important only for the hottest and densest H II regions. The non-LTE calculations were checked through a comparison derivation of electron temperatures using hydrogen beta lines

  18. Phenylbutyrate inhibits homologous recombination induced by camptothecin and methyl methanesulfonate

    DEFF Research Database (Denmark)

    Kaiser, Gitte Schalck; Germann, Susanne Manuela; Westergaard, Tine;

    2011-01-01

    Homologous recombination is accompanied by extensive changes to chromatin organization at the site of DNA damage. Some of these changes are mediated through acetylation/deacetylation of histones. Here, we show that recombinational repair of DNA damage induced by the anti-cancer drug camptothecin...

  19. The Λ0 polarization and the recombination mechanism

    International Nuclear Information System (INIS)

    We use the recombination and the Thomas Precession Model to obtain a prediction for the Λ0 polarization in the p+p → Λ0 + X reaction. We study the effect of the recombination function on the Λ0 polarization. (author)

  20. Recombination in Avian Gamma-Coronavirus Infectious Bronchitis Virus

    Directory of Open Access Journals (Sweden)

    Mark W. Jackwood

    2011-09-01

    Full Text Available Recombination in the family Coronaviridae has been well documented and is thought to be a contributing factor in the emergence and evolution of different coronaviral genotypes as well as different species of coronavirus. However, there are limited data available on the frequency and extent of recombination in coronaviruses in nature and particularly for the avian gamma-coronaviruses where only recently the emergence of a turkey coronavirus has been attributed solely to recombination. In this study, the full-length genomes of eight avian gamma-coronavirus infectious bronchitis virus (IBV isolates were sequenced and along with other full-length IBV genomes available from GenBank were analyzed for recombination. Evidence of recombination was found in every sequence analyzed and was distributed throughout the entire genome. Areas that have the highest occurrence of recombination are located in regions of the genome that code for nonstructural proteins 2, 3 and 16, and the structural spike glycoprotein. The extent of the recombination observed, suggests that this may be one of the principal mechanisms for generating genetic and antigenic diversity within IBV. These data indicate that reticulate evolutionary change due to recombination in IBV, likely plays a major role in the origin and adaptation of the virus leading to new genetic types and strains of the virus.

  1. Momentum-space calculation of four-boson recombination

    OpenAIRE

    Deltuva, A.

    2012-01-01

    The system of four identical bosons with large two-boson scattering length is described using momentum-space integral equations for the four-particle transition operators. The creation of Efimov trimers via ultracold four-boson recombination is studied. The universal behavior of the recombination rate is demonstrated.

  2. Dissociative recombination of HeH[sup +]: A reexamination

    Energy Technology Data Exchange (ETDEWEB)

    Yousif, F.B.; Mitchell, J.B.A.; Rogelstad, M.; Le Paddelec, A.; Canosa, A.; Chibisov, M.I. (Department of Physics and Center for Chemical Physics, University of Western Ontario, London, Ontario, N6A3K7 (Canada))

    1994-06-01

    A high-energy-resolution study of the dissociative recombination of HeH[sup +] has been performed. A theoretical analysis has indicated that the recombination at low energy is due to the presence of a metastable triplet-state component of the ion beam.

  3. A Heritable Recombination system for synthetic Darwinian evolution in yeast.

    Science.gov (United States)

    Romanini, Dante W; Peralta-Yahya, Pamela; Mondol, Vanessa; Cornish, Virginia W

    2012-12-21

    Genetic recombination is central to the generation of molecular diversity and enhancement of evolutionary fitness in living systems. Methods such as DNA shuffling that recapitulate this diversity mechanism in vitro are powerful tools for engineering biomolecules with useful new functions by directed evolution. Synthetic biology now brings demand for analogous technologies that enable the controlled recombination of beneficial mutations in living cells. Thus, here we create a Heritable Recombination system centered around a library cassette plasmid that enables inducible mutagenesis via homologous recombination and subsequent combination of beneficial mutations through sexual reproduction in Saccharomyces cerevisiae. Using repair of nonsense codons in auxotrophic markers as a model, Heritable Recombination was optimized to give mutagenesis efficiencies of up to 6% and to allow successive repair of different markers through two cycles of sexual reproduction and recombination. Finally, Heritable Recombination was employed to change the substrate specificity of a biosynthetic enzyme, with beneficial mutations in three different active site loops crossed over three continuous rounds of mutation and selection to cover a total sequence diversity of 10(13). Heritable Recombination, while at an early stage of development, breaks the transformation barrier to library size and can be immediately applied to combinatorial crossing of beneficial mutations for cell engineering, adding important features to the growing arsenal of next generation molecular biology tools for synthetic biology. PMID:23412545

  4. Electron recombination with tungsten ions with open f-shells

    CERN Document Server

    Harabati, C; Flambaum, V V; Dzuba, V A

    2016-01-01

    We calculate the electron recombination rates with target ions W$^{q+}$, $q = 18$ -- $25$, as functions of electron energy and electron temperature (i.e. the rates integrated over the Maxwellian velocity distribution). Comparison with available experimental data for W$^{18+}$, W$^{19+}$, and W$^{20+}$ is used as a test of our calculations. Our predictions for W$^{21+}$, W$^{22+}$, W$^{23+}$, W$^{24+}$, and W$^{25+}$ (where the experimental data are not available) may be used for plasma modelling in thermonuclear reactors. All of these ions have an open electron $f$-shell and have an extremely dense spectrum of chaotic many-electron compound resonances which enhance the recombination rates by 2-3 orders of magnitude in comparison with the direct electron recombination. Conventional dielectronic recombination theory is not directly applicable in this case. Instead, we developed a statistical theory based on the properties of chaotic eigenstates. This theory describes a multi-electronic recombination (extension ...

  5. Recombinant human bone morphogenetic protein induces bone formation

    International Nuclear Information System (INIS)

    The authors have purified and characterized active recombinant human bone morphogenetic protein (BMP) 2A. Implantation of the recombinant protein in rats showed that a single BMP can induce bone formation in vivo. A dose-response and time-course study using the rat ectopic bone formation assay revealed that implantation of 0.5-115 μg of partially purified recombinant human BMP-2A resulted in cartilage by day 7 and bone formation by day 14. The time at which bone formation occurred was dependent on the amount of BMP-2A implanted; at high doses bone formation could be observed at 5 days. The cartilage- and bone-inductive activity of the recombinant BMP-2A is histologically indistinguishable from that of bone extracts. Thus, recombinant BMP-2A has therapeutic potential to promote de novo bone formation in humans

  6. CRISPR-directed mitotic recombination enables genetic mapping without crosses.

    Science.gov (United States)

    Sadhu, Meru J; Bloom, Joshua S; Day, Laura; Kruglyak, Leonid

    2016-05-27

    Linkage and association studies have mapped thousands of genomic regions that contribute to phenotypic variation, but narrowing these regions to the underlying causal genes and variants has proven much more challenging. Resolution of genetic mapping is limited by the recombination rate. We developed a method that uses CRISPR (clustered, regularly interspaced, short palindromic repeats) to build mapping panels with targeted recombination events. We tested the method by generating a panel with recombination events spaced along a yeast chromosome arm, mapping trait variation, and then targeting a high density of recombination events to the region of interest. Using this approach, we fine-mapped manganese sensitivity to a single polymorphism in the transporter Pmr1. Targeting recombination events to regions of interest allows us to rapidly and systematically identify causal variants underlying trait differences. PMID:27230379

  7. Sex recombination, and reproductive fitness: an experimental study using Paramecium

    Energy Technology Data Exchange (ETDEWEB)

    Nyberg, D.

    1982-08-01

    The effect of sex and recombination on reproductive fitness are measured using five wild stocks of Paramecium primaurelia. Among the wild stocks there were highly significant differences in growth rates. No hybrid had as low a fitness as the least fit parental stock. Recombination produced genotypes of higher fitness than those of either parent only in the cross between the two stocks of lowest fitness. The increase in variance of fitness as a result of recombination was almost exclusively attributable to the generation lines with low fitness. The fitness consequences of sexuality and mate choice were stock specific; some individuals leaving the most descendants by inbreeding, others by outcrossing. For most crosses the short-term advantage of sex, if any, accrue from the fusion of different gametes (hybrid vigor) and not from recombination. Since the homozygous genotype with the highest fitnes left the most progeny by inbreeding (no recombination), the persistence of conjugation in P. primaurelia is paradoxical. (JMT)

  8. Patterns of Human Immunodeficiency Virus type 1 recombination ex vivo provide evidence for coadaptation of distant sites, resulting in purifying selection for intersubtype recombinants during replication

    DEFF Research Database (Denmark)

    Galli, Andrea; Kearney, Mary; Nikolaitchik, Olga A;

    2010-01-01

    in human populations. We hypothesize that sequence diversity affects the emergence of viable recombinants by decreasing recombination events and reducing the ability of the recombinants to replicate. To test our hypothesis, we compared recombination between two viruses containing subtype B pol genes (B...

  9. Multiple barriers to recombination between divergent HIV-1 variants revealed by a dual-marker recombination assay

    DEFF Research Database (Denmark)

    Nikolaitchik, Olga A; Galli, Andrea; Moore, Michael D;

    2011-01-01

    Recombination is a major force for generating human immunodeficiency virus type 1 (HIV-1) diversity and produces numerous recombinants circulating in the human population. We previously established a cell-based system using green fluorescent protein gene (gfp) as a reporter to study the mechanisms...

  10. Effects of the rad52 gene on recombination in Saccharomyces cerevisiae. [Comparison of. gamma. -, uv-induced meiotic and spontaneous mitotic recombination

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, S.; Prakash, L.; Burke, W.; Montelone, B.A.

    1979-01-01

    Effects of the rad52 mutation in Saccharomyces cerevisiae on meiotic, ..gamma..-ray-induced, uv-induced, and spontaneous mitotic recombination were studied. The rad52/rad52 diploids undergo premeiotic DNA synthesis; sporulation occurs but inviable spores are produced. Intra- and intergenic recombination during meiosis were examined in cells transferred from sporulation medium to vegetative medium at different time intervals. No intragenic recombination was observed at the hisl-1/hisl-315 and trp5-2/trp5-48 heteroalleles. Gene-centromere recombination was also not observed in rad52/rad52 diploids. No ..gamma..-ray-induced intragenic mitotic recombination is seen in rad52/rad52 diploids and uv-induced intragenic recombination is greatly reduced. However, spontaneous mitotic recombination is not similarly affected. The RAD52 gene thus functions in recombination in meiosis and in ..gamma..-ray and uv-induced mitotic recombination but not in spontaneous mitotic recombination.

  11. Numerical Study of Passive Catalytic Recombiner for Hydrogen Mitigation

    Directory of Open Access Journals (Sweden)

    Pavan K Sharma

    2010-10-01

    Full Text Available A significant amount of hydrogen is expected to be released within the containment of a water cooled power reactor after a severe accident. To reduce the risk of deflagration/detonation various means for hydrogen control have been adopted all over the world. Passive catalytic recombiner with vertical flat catalytic plate is one of such hydrogen mitigating device. Passive catalytic recombiners are designed for the removal of hydrogen generated in order to limit the impact of possible hydrogen combustion. Inside a passive catalytic recombiner, numerous thin steel sheets coated with catalyst material are vertically arranged at the bottom opening of a sheet metal housing forming parallel flow channels for the surrounding gas atmosphere. Already below conventional flammability limits, hydrogen and oxygen react exothermally on the catalytic surfaces forming harmless steam. Detailed numerical simulations and experiments are required for an in-depth knowledge of such plate type catalytic recombiners. Specific finite volume based in-house CFD code has been developed to model and analyse the working of these recombiner. The code has been used to simulate the recombiner device used in the Gx-test series of Battelle-Model Containment (B-MC experiments. The present paper briefly describes the working principle of such passive catalytic recombiner and salient feature of the CFD model developed at Bhabha Atomic Research Centre (BARC. Finally results of the calculations and comparison with existing data are discussed.

  12. Phylogenetic and recombination analysis of tomato spotted wilt virus.

    Directory of Open Access Journals (Sweden)

    Sen Lian

    Full Text Available Tomato spotted wilt virus (TSWV severely damages and reduces the yield of many economically important plants worldwide. In this study, we determined the whole-genome sequences of 10 TSWV isolates recently identified from various regions and hosts in Korea. Phylogenetic analysis of these 10 isolates as well as the three previously sequenced isolates indicated that the 13 Korean TSWV isolates could be divided into two groups reflecting either two different origins or divergences of Korean TSWV isolates. In addition, the complete nucleotide sequences for the 13 Korean TSWV isolates along with previously sequenced TSWV RNA segments from Korea and other countries were subjected to phylogenetic and recombination analysis. The phylogenetic analysis indicated that both the RNA L and RNA M segments of most Korean isolates might have originated in Western Europe and North America but that the RNA S segments for all Korean isolates might have originated in China and Japan. Recombination analysis identified a total of 12 recombination events among all isolates and segments and five recombination events among the 13 Korea isolates; among the five recombinants from Korea, three contained the whole RNA L segment, suggesting reassortment rather than recombination. Our analyses provide evidence that both recombination and reassortment have contributed to the molecular diversity of TSWV.

  13. Insect Larvae: A New Platform to Produce Commercial Recombinant Proteins.

    Science.gov (United States)

    Targovnik, Alexandra M; Arregui, Mariana B; Bracco, Lautaro F; Urtasun, Nicolas; Baieli, Maria F; Segura, Maria M; Simonella, Maria A; Fogar, Mariela; Wolman, Federico J; Cascone, Osvaldo; Miranda, Maria V

    2016-01-01

    In Biotechnology, the expression of recombinant proteins is a constantly growing field and different hosts are used for this purpose. Some valuable proteins cannot be produced using traditional systems. Insects from the order Lepidoptera infected with recombinant baculovirus have appeared as a good choice to express high levels of proteins, especially those with post-translational modifications. Lepidopteran insects, which are extensively distributed in the world, can be used as small protein factories, the new biofactories. Species like Bombyx mori (silkworm) have been analyzed in Asian countries to produce a great number of recombinant proteins for use in basic and applied science and industry. Many proteins expressed in this larva have been commercialized. Several recombinant proteins produced in silkworms have already been commercialized. On the other hand, species like Spodoptera frugiperda, Heliothis virescens, Rachiplusia nu, Helicoverpa zea and Trichoplusia ni are widely distributed in both the occidental world and Europe. The expression of recombinant proteins in larvae has the advantage of its low cost in comparison with insect cell cultures. A wide variety of recombinant proteins, including enzymes, hormones and vaccines, have been efficiently expressed with intact biological activity. The expression of pharmaceutically proteins, using insect larvae or cocoons, has become very attractive. This review describes the use of insect larvae as an alternative to produce commercial recombinant proteins. PMID:26956108

  14. Two complementary recombinant chromosomes 5 in a healthy woman.

    Science.gov (United States)

    Bartsch, O; Ergun, M A; Balci, S; Kan, D; Eggermann, T; Kotzot, D

    2006-01-01

    We report a healthy woman with two abortions who is a carrier for a rare heterozygous double recombinant of an inv(5) chromosome, karyotype 46,XX,rec(5)dup(5p) inv(5)(p13q22),rec(5)dup(5q)inv(5)(p13q22). Her father had a 46,XY,inv(5)(p13q22) karyotype; his consanguineous wife had died. Molecular investigation of 11 highly polymorphic markers spanning chromosome 5 revealed biparental inheritance for two markers (D5S406, D5S681) on 5p15.3 and 5q13.1, and an allele constellation not compatible with paternal heterodisomy for marker D5S623 on 5q11.2. Eight markers were not informative. Three mechanisms of formation are proposed: First, fertilization of a normal oocyte by a sperm carrying the two recombinant chromosomes 5, followed by postzygotic recombination between the normal maternal homologue and the rec(5)dup(5p), and by loss of the mitotically recombined maternal homologue, leading to segmental paternal heterodisomy 5q13-->qter (trisomic rescue). Second, postzygotic recombination in a 46,XX,inv(5)(p13q22) zygote resulting in the 46,XX,rec(5)dup(5p)inv(5)(p13q22),rec(5) dup(5q)inv(5)(p13q22) karyotype, followed by absence of the original cell line in lymphocytes. Third and most likely, both parents were inv(5) carriers and complementary recombinations in maternal and paternal meiosis resulted in a zygote with two recombinant chromosomes 5. Our patient refused any further studies but later reported the birth of a phenotypically normal child. This is the first report known to us of complementation by two non-homologous recombinant chromosomes in a phenotypically normal woman, and the first example of a child born to a carrier of complementary recombinant chromosomes. PMID:16825772

  15. Recombinant phage probes for Listeria monocytogenes

    International Nuclear Information System (INIS)

    Monitoring of food and environmental samples for biological threats, such as Listeria monocytogenes, requires probes that specifically bind biological agents and ensure their immediate and efficient detection. There is a need for robust and inexpensive affinity probes as an alternative to antibodies. These probes may be recruited from random peptide libraries displayed on filamentous phage. In this study, we selected from two phage peptide libraries phage clones displaying peptides capable of specific and strong binding to the L. monocytogenes cell surface. The ability of isolated phage clones to interact specifically with L. monocytogenes was demonstrated using enzyme-linked immunosorbent assay (ELISA) and confirmed by co-precipitation assay. We also assessed the sensitivity of phage-bacteria binding by PCR on phage-captured Listeria cells, which could be detected at a concentration of 104 cells ml-1. In addition, as proof-of-concept, we tested the possibility of immobilizing the affinity-selected phages to a putative biosensor surface. The quality of phage deposition was monitored by ELISA and fluorescent microscopy. Phage-bacterial binding was confirmed by high power optical phase contrast microscopy. Overall, the results of this work validate the concept of affinity-selected recombinant filamentous phages as probes for detecting and monitoring bacterial agents under any conditions that warrant their recognition, including in food products

  16. Recombinant phage probes for Listeria monocytogenes

    Energy Technology Data Exchange (ETDEWEB)

    Carnazza, S; Gioffre, G; Felici, F; Guglielmino, S [Department of Microbiological, Genetic and Molecular Sciences, University of Messina, Messina (Italy)

    2007-10-03

    Monitoring of food and environmental samples for biological threats, such as Listeria monocytogenes, requires probes that specifically bind biological agents and ensure their immediate and efficient detection. There is a need for robust and inexpensive affinity probes as an alternative to antibodies. These probes may be recruited from random peptide libraries displayed on filamentous phage. In this study, we selected from two phage peptide libraries phage clones displaying peptides capable of specific and strong binding to the L. monocytogenes cell surface. The ability of isolated phage clones to interact specifically with L. monocytogenes was demonstrated using enzyme-linked immunosorbent assay (ELISA) and confirmed by co-precipitation assay. We also assessed the sensitivity of phage-bacteria binding by PCR on phage-captured Listeria cells, which could be detected at a concentration of 10{sup 4} cells ml{sup -1}. In addition, as proof-of-concept, we tested the possibility of immobilizing the affinity-selected phages to a putative biosensor surface. The quality of phage deposition was monitored by ELISA and fluorescent microscopy. Phage-bacterial binding was confirmed by high power optical phase contrast microscopy. Overall, the results of this work validate the concept of affinity-selected recombinant filamentous phages as probes for detecting and monitoring bacterial agents under any conditions that warrant their recognition, including in food products.

  17. Therapeutic Use of Native and Recombinant Enteroviruses

    Directory of Open Access Journals (Sweden)

    Jani Ylä-Pelto

    2016-02-01

    Full Text Available Research on human enteroviruses has resulted in the identification of more than 100 enterovirus types, which use more than 10 protein receptors and/or attachment factors required in cell binding and initiation of the replication cycle. Many of these “viral” receptors are overexpressed in cancer cells. Receptor binding and the ability to replicate in specific target cells define the tropism and pathogenesis of enterovirus types, because cellular infection often results in cytolytic response, i.e., disruption of the cells. Viral tropism and cytolytic properties thus make native enteroviruses prime candidates for oncolytic virotherapy. Copy DNA cloning and modification of enterovirus genomes have resulted in the generation of enterovirus vectors with properties that are useful in therapy or in vaccine trials where foreign antigenic epitopes are expressed from or on the surface of the vector virus. The small genome size and compact particle structure, however, set limits to enterovirus genome modifications. This review focuses on the therapeutic use of native and recombinant enteroviruses and the methods that have been applied to modify enterovirus genomes for therapy.

  18. Therapeutic Use of Native and Recombinant Enteroviruses.

    Science.gov (United States)

    Ylä-Pelto, Jani; Tripathi, Lav; Susi, Petri

    2016-03-01

    Research on human enteroviruses has resulted in the identification of more than 100 enterovirus types, which use more than 10 protein receptors and/or attachment factors required in cell binding and initiation of the replication cycle. Many of these "viral" receptors are overexpressed in cancer cells. Receptor binding and the ability to replicate in specific target cells define the tropism and pathogenesis of enterovirus types, because cellular infection often results in cytolytic response, i.e., disruption of the cells. Viral tropism and cytolytic properties thus make native enteroviruses prime candidates for oncolytic virotherapy. Copy DNA cloning and modification of enterovirus genomes have resulted in the generation of enterovirus vectors with properties that are useful in therapy or in vaccine trials where foreign antigenic epitopes are expressed from or on the surface of the vector virus. The small genome size and compact particle structure, however, set limits to enterovirus genome modifications. This review focuses on the therapeutic use of native and recombinant enteroviruses and the methods that have been applied to modify enterovirus genomes for therapy. PMID:26907330

  19. Recombinant phage probes for Listeria monocytogenes

    Science.gov (United States)

    Carnazza, S.; Gioffrè, G.; Felici, F.; Guglielmino, S.

    2007-10-01

    Monitoring of food and environmental samples for biological threats, such as Listeria monocytogenes, requires probes that specifically bind biological agents and ensure their immediate and efficient detection. There is a need for robust and inexpensive affinity probes as an alternative to antibodies. These probes may be recruited from random peptide libraries displayed on filamentous phage. In this study, we selected from two phage peptide libraries phage clones displaying peptides capable of specific and strong binding to the L. monocytogenes cell surface. The ability of isolated phage clones to interact specifically with L. monocytogenes was demonstrated using enzyme-linked immunosorbent assay (ELISA) and confirmed by co-precipitation assay. We also assessed the sensitivity of phage-bacteria binding by PCR on phage-captured Listeria cells, which could be detected at a concentration of 104 cells ml-1. In addition, as proof-of-concept, we tested the possibility of immobilizing the affinity-selected phages to a putative biosensor surface. The quality of phage deposition was monitored by ELISA and fluorescent microscopy. Phage-bacterial binding was confirmed by high power optical phase contrast microscopy. Overall, the results of this work validate the concept of affinity-selected recombinant filamentous phages as probes for detecting and monitoring bacterial agents under any conditions that warrant their recognition, including in food products.

  20. Developing recombinant antibodies for biomarker detection

    Energy Technology Data Exchange (ETDEWEB)

    Baird, Cheryl L.; Fischer, Christopher J.; Pefaur, Noah B.; Miller, Keith D.; Kagen, Jacob; Srivastava, Sudhir; Rodland, Karin D.

    2010-10-01

    Monoclonal antibodies (mAbs) have an essential role in biomarker validation and diagnostic assays. A barrier to pursuing these applications is the reliance on immunization and hybridomas to produce mAbs, which is time-consuming and may not yield the desired mAb. We recommend a process flow for affinity reagent production that utilizes combinatorial protein display systems (eg, yeast surface display or phage display) rather than hybridomas. These systems link a selectable phenotype-binding conferred by an antibody fragment-with a means for recovering the encoding gene. Recombinant libraries obtained from immunizations can produce high-affinity antibodies (<10 nM) more quickly than other methods. Non-immune libraries provide an alternate route when immunizations are not possible, or when suitable mAbs are not recovered from an immune library. Directed molecular evolution (DME) is an integral part of optimizing mAbs obtained from combinatorial protein display, but can also be used on hybridoma-derived mAbs. Variants can easily be obtained and screened to increase the affinity of the parent mAb (affinity maturation). We discuss examples where DME has been used to tailor affinity reagents to specific applications. Combinatorial protein display also provides an accessible method for identifying antibody pairs, which are necessary for sandwich-type diagnostic assays.

  1. Belgian NPPS fit passive autocatalytic recombiners

    International Nuclear Information System (INIS)

    Because hydrogen production during severe accidents can endanger the containment or safety-graded equipment, the Belgian Utility requested Belgatom in 1989 to perform a comparative study between the possible mitigative measures. From the outcome of that study, the Utility decided to install Passive Autorcatalytic Recombiners (PARs) in the seven Belgian units and mandated Belgatom to carry out the project. The author presents the successive steps from the principle decision to the installation on site. A first section is devoted to the sizing of the catalytic surface and its distribution inside the containment. The results of the method are presented for the 5 units equipped before October 96. Besides the functional requirements, the catalyst must also resist to poisoning agents which can be released not only during severe accidents but also during normal operation or shutdown; the relevant qualification criteria are reminded in the second section. Because the installation of the PARs requires also the design of supports, recommendations are drawn to minimize the design effort and the assembling work. At last, the effectiveness of the PARs entirely relies on a catalyst material of which the potential has to be periodically controlled. A section briefly describes the in-service inspection and the related test procedures

  2. Development of recombinant vaccines for botulinum neurotoxin.

    Science.gov (United States)

    Smith, L A

    1998-11-01

    Synthetic genes encoding non-toxic, carboxyl-terminal regions (approximately 50 kDa) of botulinum neurotoxin (BoNT) serotypes A and B (referred to as fragment C or HC) were constructed and cloned into the methylotropic yeast, Pichia pastoris. Genes specifying BoNTA(HC) and BoNTB(HC) were expressed as both intracellular and secreted products. Recombinants, expressed intracellularly, yielded products with the expected molecular weight as judged by SDS PAGE and Western blot (immunoblot) analysis, while secreted products were larger due to glycosylation. Gene products were used to vaccinate mice and evaluated for their ability to elicit protective antibody titers in vivo. Mice given three intramuscular vaccinations with yeast supernatant containing glycosylated BoNTA(HC) were protected against an intraperitoneal challenge of 10(6) 50% mouse lethal doses (MLD50) of serotype A neurotoxin, a result not duplicated by its BoNTB(HC) counterpart. Vaccinating mice with cytoplasmically produced BoNTA(HC) and BoNTB(HC) protected animals from a challenge of 10(6) MLD50 of serotype A and B toxins, respectively. Because of the glycosylation encountered with secreted BoNT(HC), our efforts focused on the production and purification of products from intracellular expression. PMID:9792170

  3. Recombination, extrachromosomal dna and genome stability

    International Nuclear Information System (INIS)

    Eukaryotic chromosomes are faithfully transmitted from one generation to another. However, eukaryotic genomes are much more dynamic than this view permits. Repetitive sequences are among the most rapidly evolving genome constituents and copy number variations are extremely abundant even within species. Rapid evolution of repetitive DNA is particularly apparent during domestication of many crops and is, for example, well documented in cereals such as maize or barley. Importantly, deletions or insertions of such sequences may contribute to variation in protein-coding gene expression. This can occur by altering gene copy number and expression, by disrupting regulatory sequences or by altering regulatory RNA production. One mechanism that may significantly contribute to copy number variation and rapid evolution of crop genomes involves the formation of extrachromosomal circular DNA molecules (eccs). I will present evidence for eccDNA derived from centromeres, 5S rDNA and telomeres in Arabidopsis. I will further discuss the role of homologous recombination, telomere metabolism and chromatin modification in eccDNA biogenesis. Finally, I will discuss the impact of eccDNA metabolism on the stability and evolution of plant genomes. (author)

  4. Homologous recombination deficiency and ovarian cancer.

    Science.gov (United States)

    Ledermann, Jonathan A; Drew, Yvette; Kristeleit, Rebecca S

    2016-06-01

    The discovery that PARP inhibitors block an essential pathway of DNA repair in cells harbouring a BRCA mutation has opened up a new therapeutic avenue for high-grade ovarian cancers. BRCA1 and BRCA2 proteins are essential for high-fidelity repair of double-strand breaks of DNA through the homologous recombination repair (HRR) pathway. Deficiency in HRR (HRD) is a target for PARP inhibitors. The first PARP inhibitor, olaparib, has now been licensed for BRCA-mutated ovarian cancers. While mutated BRCA genes are individually most commonly associated with HRD other essential HRR proteins may be mutated or functionally deficient potentially widening the therapeutic opportunities for PARP inhibitors. HRD is the first phenotypically defined predictive marker for therapy with PARP inhibitors in ovarian cancer. Several different PARP inhibitors are being trialled in ovarian cancer and this class of drugs has been shown to be a new selective therapy for high-grade ovarian cancer. Around 20% of high-grade serous ovarian cancers harbour germline or somatic BRCA mutations and testing for BRCA mutations should be incorporated into routine clinical practice. The expanded use of PARP inhibitors in HRD deficient (non-BRCA mutant) tumours using a signature of HRD in clinical practice requires validation. PMID:27065456

  5. Recombinative generalization of subword units using matching to sample.

    LENUS (Irish Health Repository)

    Mahon, Catherine

    2010-01-01

    The purpose of the current study was to develop and test a computerized matching-to-sample (MTS) protocol to facilitate recombinative generalization of subword units (onsets and rimes) and recognition of novel onset-rime and onset-rime-rime words. In addition, we sought to isolate the key training components necessary for recombinative generalization. Twenty-five literate adults participated. Conditional discrimination training emerged as a crucial training component. These findings support the effectiveness of MTS in facilitating recombinative generalization, particularly when conditional discrimination training with subword units is used.

  6. Recombinant protein expression in Escherichia coli: advances and challenges

    Directory of Open Access Journals (Sweden)

    GermánLeandroRosano

    2014-04-01

    Full Text Available Escherichia coli is the organism of choice for the production of recombinant proteins. Its use as a cell factory is well-established and it has become the most popular expression platform. For this reason, there are many molecular tools and protocols at hand for the high-level production of recombinant proteins, such as a vast catalog of expression plasmids, a great number of engineered strains and many cultivation strategies. We review the different approaches for the synthesis of recombinant proteins in E. coli and discuss recent progress in this ever-growing field.

  7. Sequence and recombination analyses of the geminivirus replication initiator protein

    Indian Academy of Sciences (India)

    T Vadivukarasi; K R Girish; R Usha

    2007-01-01

    The sequence motifs present in the replication initiator protein (Rep) of geminiviruses have been compared with those present in all known rolling circle replication initiators. The predicted secondary structures of Rep representing each group of organisms have been compared and found to be conserved. Regions of recombination in the Rep gene and the adjoining 5′ intergenic region (IR) of representative species of Geminiviridae have been identified using Recombination Detection Programs. The possible implications of such recombinations on the increasing host range of geminivirus infections are discussed.

  8. Fitness-associated recombination on rugged adaptive landscapes.

    Science.gov (United States)

    Hadany, L; Beker, T

    2003-09-01

    A negative correlation between fitness and recombination rates seems to exist in various organisms. In this article we suggest that a correlation of that kind may play an important role in the evolution of complex traits. We study the effects of such fitness-associated recombination (FAR) in a simple two-locus deterministic model, as well as in a multi-loci NK rugged adaptive landscape. In both models studied, FAR results in faster adaptation and higher average population fitness, compared with uniform-rate recombination. PMID:14635901

  9. Charges recombination in α particle tracks in argon

    International Nuclear Information System (INIS)

    The creation and evolution of (neutral) excited states and ionized states in α particle tracks in high pressure argon are studied. The main features of recently published experimental results on the recombination luminescence can be explained and a track model is proposed. Details are given on the track radius, on the electrons thermallization, and on collisions between electrons and triplet excited states. The most important result is that at high pressure and high electron and ion densities a collective electron-ion recombination is possible, that is more efficient that the well known dissociative recombination

  10. Stimulated radiative recombination of H{sup +} and He {sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Rogelstad, M.L.; Mitchell, J.B.A. [Western Ontario Univ., Physics Dept., London, ON (Canada); Yousif, F.B. [UNAM, Inst. de Fisica, Cuernavaca (Mexico); Morgan, T.J. [Wesleyan Univ., Physics Dept., Middletown, CT (United States)

    1997-09-14

    Stimulated radiative recombination has been demonstrated experimentally in e{sup -}+H{sup +} and e{sup -} + He{sup +} collisions using a merged electron-ion beams apparatus with field ionization detection of the excited neutral products. Enhancement of the recombination over spontaneous recombination to form the n = 11, 12 and 13 levels of atomic hydrogen and the n = 11 and 12 levels of atomic helium by factors of between 1000 and 3000 have been found using a CO{sub 2} laser power of 8 W. Evidence for the resolution of fine-structure levels has been seen for the case of helium. (author).

  11. Dynamics of carrier recombination in a semiconductor laser structure

    Energy Technology Data Exchange (ETDEWEB)

    Dzhioev, R. I., E-mail: dzhioev@orient.ioffe.ru; Kavokin, K. V.; Kusrayev, Yu. G.; Poletaev, N. K. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2015-11-15

    Carrier-recombination dynamics is studied by the method of optical orientation at room temperature in the active layer of a laser diode structure. The dependence of the degree of electron-spin orientation on the excitation density is attributed to saturation of the nonradiative-recombination channel. The time of electron capture at recombination centers is determined to be τ{sub e} = 5 × 10{sup –9} s. The temperature of nonequilibrium electrons heated by a He–Ne laser is estimated.

  12. RecQ Promotes Toxic Recombination in Cells Lacking Recombination-Intermediate-Removal Proteins

    OpenAIRE

    Magner, Daniel B.; Blankschien, Matthew D.; Lee, Jennifer A.; Pennington, Jeanine M.; James R. Lupski; Rosenberg, Susan M.

    2007-01-01

    The RecQ-helicase family is widespread, highly conserved, and includes human orthologues that suppress genomic instability and cancer. In vivo, some RecQ homologues promote reduction of steady-state levels of bimolecular recombination intermediates (BRIs), which block chromosome segregation if not resolved. We find that in vivo, E. coli RecQ can promote the opposite: the net accumulation of BRIs. We report that cells lacking Ruv and UvrD BRI-resolution and -prevention proteins die and display...

  13. The use of recombinant DNA plasmids for the determination of DNA-repair and recombination in cultured mammalian cells.

    OpenAIRE

    Cox, R.; Masson, W. K.; Debenham, P G; Webb, M. B.

    1984-01-01

    Using the recombinant plasmid pSV2gpt and DNA transfer techniques, cell mediated DNA ligation and recombination of plasmid DNA have been demonstrated in four human cell lines. Data suggesting the involvement of a possible defect in the cellular equilibrium between ligation and exonuclease digestion of double strand DNA scissions in an ataxia-telangiectasia (A-T) cell line is discussed. The same A-T line was grossly proficient in DNA recombination but it will be necessary to distinguish betwee...

  14. Recombination of atomic oxygen and hydrogen on amorphous carbon

    International Nuclear Information System (INIS)

    Deposit buildup and fuel entrapment due to amorphous carbon are relevant issues in fusion devices with carbon based plasma facing components. Neutral atomic species play a significant role – atomic hydrogen facilitates the formation of amorphous carbon while atomic oxygen could be used to remove carbon deposits. The kinetics of either reaction depends on the density of neutral species, which in turn is influenced by recombination on the vessel walls. In this work, we measured the probability of heterogeneous recombination of atomic hydrogen and oxygen on amorphous carbon deposits. The recombination coefficients were determined by observing density profiles of atomic species in a closed side-arm of a plasma vessel with amorphous carbon deposit-lined walls. Density profiles were measured with fiber optics catalytic probes. The source of atomic species was inductively coupled radiofrequency plasma. The measured recombination coefficient values were of the order of 10−3 for both species

  15. Nonradiative recombination of excitons in semimagnetic quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Chernenko, A. V., E-mail: chernen@issp.ac.ru [Russian Academy of Sciences, Institute of Solid State Physics (Russian Federation)

    2015-12-15

    The mechanisms of the nonradiative recombination of excitons in neutral and charged quantum dots based on II–VI semimagnetic semiconductors are investigated. It is shown that, along with the dipole–dipole and direct-exchange mechanisms, there is one more mechanism referred to as the indirect-exchange mechanism and related to sp–d mixing. The selection rules for nonradiative recombination by exchange mechanisms are subsequently derived. The dependence of the efficiency of all recombination mechanisms on the quantum-dot size is studied. The experimentally observed growth in the intracenter photoluminescence intensity with decreasing size of dots and nanocrystals is accounted for. Methods for experimental determination of the contributions of different mechanisms to nonradiative recombination are discussed.

  16. Meiotic recombination in normal and cloned bulls and their offspring

    Science.gov (United States)

    Homologous chromosome pairing and recombination are essential components of meiosis and sexual reproduction. The reshuffling of genetic material through breakage and reunion of chromatids ensure proper segregation of homologous chromosomes in reduction division and genetic diversity in the progeny....

  17. Non-Enzymatic Template-Directed Recombination of RNAs

    Directory of Open Access Journals (Sweden)

    Marina A. Zenkova

    2009-04-01

    Full Text Available RNA non-enzymatic recombination reactions are of great interest within the hypothesis of the "RNA world", which argues that at some stage of prebiotic life development proteins were not yet engaged in biochemical reactions and RNA carried out both the information storage task and the full range of catalytic roles necessary in primitive self-replicating systems. Here we report on the study of recombination reaction occuring between two 96 nucleotides (nts fragments of RNAs under physiological conditions and governed by a short oligodeoxyribonucleotide template, partially complementary to sequences within each of the RNAs. Analysis of recombination products shows that ligation is predominantly template-directed, and occurs within the complementary complex with the template in "butt-to-butt" manner, in 1- or 3- nts bulges or in 2-3 nts internal loops. Minor recombination products formed in the template-independent manner are detected as well.

  18. Expression and purification of soluble recombinant Hexastatin in E. coli

    International Nuclear Information System (INIS)

    Purpose: To construct the expression vector of Hexastatin gene, to express and to purify the recombinant protein for further activity research. Methods: The human Hexastatin gene was isolated by RTPCR from EC9706 cells total RNA and cloned into pMD18-T for sequencing. Then the Hexastatin gene was subcloned into pMAL-c4x expression vector and induced to express by IPTG. The recombinant fusion protein was purified with Amylose Resin Heads. Results: RT-PCR product was about 687 bp and its sequence was the same as that of Hexastatin reported. The recombinant protein was expressed in E. coli BL21 with high level and the soluble protein accounted for 24.8% of the total bacterial protein. The purification of recombinant protein purified with Amylose Resin Heads reached more than 90%. Conclusion: The cloning, expression and purification of human Hexastatin have laid a foundation for its anti-angiogenesis therapy for tumor. (authors)

  19. Rate coefficients for N2(+)(v) dissociative recombination

    Science.gov (United States)

    Bates, D. R.; Mitchell, J. B. A.

    1991-09-01

    The data of Zipf (1980) on N2(+)(v) dissociative recombination are analyzed taking into account the fact that there is coupling due to reversible symmetrical resonance charge transfer, N2(+)(v) + N2(0) yields N2(+)(0) + N2(v). The vibrational deactivation in N2(+)(v)-Ne collisions is also considered. A reported experimental value of the vibrational deactivation coefficient is found to be much higher than can be reconciled with the results of Zipf and it is therefore rejected. The analysis shows that the recombination coefficient for N2(+)(0) is about 2.6 x 10 exp-7 cu cm/s at 300 K and that recombination coefficients for N2(+)(1) and N2(+)(2) are substantially smaller. It is concluded that these coefficients conflict with the dissociative recombination cross section vs energy curve obtained by the merged beam method.

  20. Phylogeny and Homologous Recombination in Japanese Encephalitis Viruses

    Institute of Scientific and Technical Information of China (English)

    Li Xiao-xue; Cong Ying-ying; Wang Xin; Ren Yu-dong; Ren Xiao-feng; Lu Ai-guo; Li Guang-xing

    2015-01-01

    Japanese encephalitis virus (JEV) is a significant causative agent of arthropod-borne encephalitis and what is less clear that the factors cause the virus wide spread. The objective was to confirm whether the homologous recombination imposed on JEV. The phylogenetic and homologous recombination analyses were performed based on 163 complete JEV genomes which were recently isolated. They were still separated into five genotypes (GI-GV) and the most of recently isolated JEVs were GI rather than GIII in Asian areas including mainland China. Two recombinant events were identified in JEV and the evidence of the recombination was observed between China and Japan isolates that partitioned into two distinct subclades, but still the same genotype (GIII). Our data further suggested that most of the nucleotides in JEV genome were under negative selection; however, changes within codon 2 316 (amino acid NS4b-44) showed an evidence of the positive selection.

  1. The evolutionary value of recombination is constrained by genome modularity.

    Directory of Open Access Journals (Sweden)

    Darren P Martin

    2005-10-01

    Full Text Available Genetic recombination is a fundamental evolutionary mechanism promoting biological adaptation. Using engineered recombinants of the small single-stranded DNA plant virus, Maize streak virus (MSV, we experimentally demonstrate that fragments of genetic material only function optimally if they reside within genomes similar to those in which they evolved. The degree of similarity necessary for optimal functionality is correlated with the complexity of intragenomic interaction networks within which genome fragments must function. There is a striking correlation between our experimental results and the types of MSV recombinants that are detectable in nature, indicating that obligatory maintenance of intragenome interaction networks strongly constrains the evolutionary value of recombination for this virus and probably for genomes in general.

  2. Experimental study of columnar recombination in fission chambers

    Science.gov (United States)

    Filliatre, P.; Lamirand, V.; Geslot, B.; Jammes, C.

    2016-05-01

    In this paper, we present experimental saturation curves of a small gap miniature fission chamber obtained in the MINERVE reactor. The chamber is filled with argon at various pressures, and the fissile material can be coated on the anode, cathode, or both. For analyzing the recombination regime, we consider a model of columnar recombination and discuss its applicability to our chamber. By applying this model to the data, it is possible to estimate the ratio between the recombination coefficient k and an effective column radius b, appearing in the model, to be k / b =(2.5 ± 0.9) ×10-6m2 / s for argon. From these results, a routine measurement of the recombination regime is proposed in order to detect gas leakage. This online diagnosis would be beneficial in terms of lifetime and reliability of the neutron instrumentation of nuclear reactors.

  3. Distant Recombination and the Creation of Basic Inventions

    DEFF Research Database (Denmark)

    Barirani, Ahmad; Beaudry, Catherine; Agard, Bruno

    2015-01-01

    This article explores whether the relationship between the breath of technological integration (recombination distance) and the breath of an invention׳s subsequent application (basicness) is moderated by the sector of activity (private or public), science-linkage strength and industry...... characteristics. Our analysis of Canadian nanotechnology patents granted between 1990 and 1997 shows that although private organizations generally yield smaller rates of basic inventions than public organizations, increases to recombination distance by the former increases invention basicness at a higher rate......; increasing reliance upon basic science moderates the relationship between recombination distance and basicness; and increases to recombination distance in emerging science-based industries increases invention basicness at a higher rate. These findings have implications regarding the debate around...

  4. Recombinant thrombomodulin for secondary thrombotic thrombocytopenic purpura.

    Science.gov (United States)

    Nakamura, Kensuke; Inokuchi, Ryota; Hiruma, Takahiro; Ohshima, Kazuma; Sonoo, Tomohiro; Tokunaga, Kurato; Doi, Kent; Nakajima, Susumu

    2016-06-01

    In the pathogenesis of thrombotic thrombocytopenic purpura (TTP), reductions in the enzyme activity of ADAMTS13, which cuts ultralarge von Willebrand multimers, generates shear stress on the microvascular endothelium, leading to platelet aggregation and the formation of a thrombus. ADAMTS13 activity is markedly decreased in typical TTP, but is only mildly reduced in secondary TTP, which concomitantly develops with primary disease. The latter develops with septic disseminated intravascular coagulation (DIC) and often causes organ failure. Recombinant thrombomodulin (rTM) is a drug that is used to treat DIC and may also remit TTP because it improves vascular endothelial dysfunction. Therefore, we herein investigated the efficacy of rTM in patients treated for the pathology of secondary TTP. Patients who were admitted to the Emergency and Critical Care Center of our hospital and met the following conditions were extracted and retrospectively analyzed: hemolytic anemia accompanied by fragmented red blood cells (Hb TTP, significantly increased in the rTM treatment group: 3.3 ± 2.6→11.3 ± 14.6 versus 3.5 ± 3.7→5.7 ± 3.9 (×1000/μL) (P = 0.034). Thrombotic thrombocytopenic purpura originally requires invasive treatments and its prognosis is not favorable. Blood thrombomodulin levels also markedly increase due to vascular endothelial dysfunction, whereas rTM alleviates vascular endothelial dysfunction in TTP patients with high blood TM levels, suggesting the importance of administering rTM. Thus, rTM may be effective for secondary TTP and may be adopted as adjuvant therapy. PMID:27310951

  5. Integrated continuous production of recombinant therapeutic proteins.

    Science.gov (United States)

    Warikoo, Veena; Godawat, Rahul; Brower, Kevin; Jain, Sujit; Cummings, Daniel; Simons, Elizabeth; Johnson, Timothy; Walther, Jason; Yu, Marcella; Wright, Benjamin; McLarty, Jean; Karey, Kenneth P; Hwang, Chris; Zhou, Weichang; Riske, Frank; Konstantinov, Konstantin

    2012-12-01

    In the current environment of diverse product pipelines, rapidly fluctuating market demands and growing competition from biosimilars, biotechnology companies are increasingly driven to develop innovative solutions for highly flexible and cost-effective manufacturing. To address these challenging demands, integrated continuous processing, comprised of high-density perfusion cell culture and a directly coupled continuous capture step, can be used as a universal biomanufacturing platform. This study reports the first successful demonstration of the integration of a perfusion bioreactor and a four-column periodic counter-current chromatography (PCC) system for the continuous capture of candidate protein therapeutics. Two examples are presented: (1) a monoclonal antibody (model of a stable protein) and (2) a recombinant human enzyme (model of a highly complex, less stable protein). In both cases, high-density perfusion CHO cell cultures were operated at a quasi-steady state of 50-60 × 10(6) cells/mL for more than 60 days, achieving volumetric productivities much higher than current perfusion or fed-batch processes. The directly integrated and automated PCC system ran uninterrupted for 30 days without indications of time-based performance decline. The product quality observed for the continuous capture process was comparable to that for a batch-column operation. Furthermore, the integration of perfusion cell culture and PCC led to a dramatic decrease in the equipment footprint and elimination of several non-value-added unit operations, such as clarification and intermediate hold steps. These findings demonstrate the potential of integrated continuous bioprocessing as a universal platform for the manufacture of various kinds of therapeutic proteins. PMID:22729761

  6. Dissociative Recombination of Molecular Ions for Astrochemistry

    Science.gov (United States)

    Novotny, Oldrich; Becker, A.; Buhr, H.; Fleischmann, Andreas; Gamer, Lisa; Geppert, W.; Krantz, C.; Kreckel, H.; Schwalm, D.; Spruck, K.; Wolf, A.; Savin, Daniel Wolf

    2014-06-01

    Dissociative recombination (DR) of molecular ions is a key chemical process in the cold interstellar medium (ISM). DR affects the composition, charge state, and energy balance of such environments. Astrochemical models of the ISM require reliable total DR cross sections as well as knowledge of the chemical composition of the neutral DR products. We have systematically measured DR for many astrophysically relevant molecular ions utilizing the TSR storage ring at the Max-Planck-Institute for Nuclear Physics (MPIK) in Heidelberg, Germany. We used the merged ion-electron beam technique combined with an energy- and position-sensitive imaging detector and are able to study DR down to plasma temperatures as low as 10 K. The DR count rate is used to obtain an absolute merged beams DR rate coefficient from which we can derive a thermal rate coefficient needed for plasma models. Additionally we determine the masses of the DR products by measuring their kinetic energy in the laboratory reference frame. This allows us to assign particular DR fragmentation channels and to obtain their branching ratios. All this information is particularly important for understanding DR of heteronuclear polyatomic ions. We will present DR results for several ions recently investigated at TSR. A new Cryogenic Storage Ring (CSR) is currently being commissioned at MPIK. With the chamber cooled down to ~10 K and a base pressure better than 10-13 mbar, this setup will allow internal cooling of the stored ions down to their rotational ground states, thus opening a new era in DR experiments. New technological challenges arise due to the ultracold, ultra-high vacuum environment of the CSR and thus the detection techniques used at TSR cannot be easily transferred to CSR. We will present new approaches for DR fragment detection in cryogenic environment. This work is supported in part by NASA and the NSF.

  7. Deficiencies of Natural Anticoagulants, Protein C, Protein S, and Antithrombin

    Science.gov (United States)

    ... citing article information Citing articles via Google Scholar Google Scholar Articles by Lipe, B. Articles by Ornstein, D. L. Search for related content PubMed PubMed citation Articles by Lipe, B. Articles by Ornstein, D. ... Reddit StumbleUpon Twitter What's this? Navigate This ...

  8. E. coli Tarafından Sentezlenen Recombinant Soyacystatinin Karakterizasyonu

    OpenAIRE

    AKPINAR, Özlem; AN, Haejung

    2004-01-01

    Recombinant (r-) soyacystatin was characterized for their inhibitory activity against papain and compared to egg white cystatin. r-Soyacystatin expressed in E. coli was purified 4.33 fold as a recombinant protein with phenyl-Sepharose and DEAE. Egg white cystatin was purified by using affinity chromatography on CM-papain-Sepharose. The specific interaction of r-soyacystatin and papain was detected on isoelectric focusing gel. Papain and r-soyacystatin formed a complex and the complex was res...

  9. Charm production asymmetries from heavy-quark recombination

    OpenAIRE

    Mehen, Thomas

    2003-01-01

    Charm asymmetries in fixed-target hadroproduction experiments are sensitive to power corrections to the QCD factorization theorem for heavy quark production. A power correction called heavy-quark recombination has recently been proposed to explain these asymmetries. In heavy-quark recombination, a light quark or antiquark participates in a hard scattering which produces a charm-anticharm quark pair. The light quark or antiquark emerges from the scattering with small momentum in the rest frame...

  10. Site-Specific Recombination Strategies for Engineering Actinomycete Genomes

    OpenAIRE

    Herrmann, Simone; Siegl, Theresa; Luzhetska, Marta; Petzke, Lutz; Jilg, Caroline; Welle, Elisabeth; Erb, Annette; Leadlay, Peter F; Bechthold, Andreas; Luzhetskyy, Andriy

    2012-01-01

    The feasibility of using technologies based on site-specific recombination in actinomycetes was shown several years ago. Despite their huge potential, these technologies mostly have been used for simple marker removal from a chromosome. In this paper, we present different site-specific recombination strategies for genome engineering in several actinomycetes belonging to the genera Streptomyces, Micromonospora, and Saccharothrix. Two different systems based on Cre/loxP and Dre/rox have been ut...

  11. Recombinant Protein Production and Insect Cell Culture and Process

    Science.gov (United States)

    Spaulding, Glenn F. (Inventor); Goodwin, Thomas J. (Inventor); OConnor, Kim C. (Inventor); Francis, Karen M. (Inventor); Andrews, Angela D. (Inventor); Prewett, Tracey L. (Inventor)

    1997-01-01

    A process has been developed for recombinant production of selected polypeptides using transformed insect cells cultured in a horizontally rotating culture vessel modulated to create low shear conditions. A metabolically transformed insect cell line is produced using the culture procedure regardless of genetic transformation. The recombinant polypeptide can be produced by an alternative process using virtually infected or stably transformed insect cells containing a gene encoding the described polypeptide. The insect cells can also be a host for viral production.

  12. Antierythropoietin Antibodies in Hemodialysis Patients Treated with Recombinant Erythropoietin

    OpenAIRE

    Savaş ÖZTÜRK; Alper GÜMÜŞ; Vecihi MEMİLİ; Muhammet Emin DÜZ; Egemen CEBECİ; Macit KOLDAŞ; Rümeyza KAZANCIOĞLU

    2014-01-01

    OBJECTIVE: Erythropoietin resistance is a serious problem in patients treated with recombinant erythropoietin. Antierythropoietin antibodies are considered to be one of the causes of this resistance. MATERIAL and ME THODS: We investigated antierythropoietin antibodies in chronic hemodialysis patients and compared the results with healthy controls by means of establishing an ELISA method. A total of 121 chronic hemodialysis patients receiving recombinant erythropoietin were included in the ...

  13. Indiscriminate recombination in simian virus 40-infected monkey cells.

    OpenAIRE

    Winocour, E; Keshet, I

    1980-01-01

    DNA transfection of African green monkey BSC-1 cells with simian virus 40 (SV40) DNA and bacterial virus phi X174 replicative form DNA ("cotransfection") yielded stocks containing SV40/phi X174 recombinant virus, which was detected by an infectious-center in situ plaque hybridization procedure and which was sensitive to anti-SV40 antiserum. The recombinant virus replicated during serial passage. Restriction endonuclease cleavage of the SV40/phi X174 DNA indicated that several different types ...

  14. Use of radioactive materials in recombinant DNA research

    International Nuclear Information System (INIS)

    Radioactively labeled compounds are used extensively in recombinant DNA work. The use of labeled compounds allows for great sensitivity of detection, essential for techniques such as DNA sequencing and genomic Southern hybridizations. DNA and RNA can be labeled to high specific activities using in vitro enzymatic reactions, and are useful in many procedures. 32P, 35S, 125I and 3H are the isotopes which are most often used in recombinant DNA studies. 20 refs

  15. The efficacy of recombinant versus urinary HCG in ART outcome

    OpenAIRE

    Maryam Eftekhar; Mohammad Ali Khalili; Elham Rahmani

    2012-01-01

    Background: Human chorionic gonadotropin (HCG) has been used as a replacement for the mid-cycle luteinizing hormone (LH) surge for several years. The recent arrival of recombinant DNA technology has made recombinant HCG (rHCG) accessible. Objective: To assess efficacy of rHCG compared to urinary HCG (uHCG) for triggering of ovulation and induction of final oocyte maturation in assisted reproductive cycles. Materials and Methods: 200 patients who were candidate for ICSI were randomly divided i...

  16. ${}^3$H production via neutron-neutron-deuteron recombination

    OpenAIRE

    Deltuva, A; Fonseca, A.C.

    2013-01-01

    We study the recombination of two neutrons and deuteron into neutron and ${}^3$H using realistic nucleon-nucleon potential models. Exact Alt, Grassberger, and Sandhas equations for the four-nucleon transition operators are solved in the momentum-space framework using the complex-energy method with special integration weights. We find that at astrophysical or laboratory neutron densities the production of ${}^3$H via the neutron-neutron-deuteron recombination is much slower as compared to the ...

  17. Non-Enzymatic Template-Directed Recombination of RNAs

    OpenAIRE

    Marina A Zenkova; Vlassov, Valentin V.; Alexei V. Lutay; Sergey Y. Nechaev

    2009-01-01

    RNA non-enzymatic recombination reactions are of great interest within the hypothesis of the "RNA world", which argues that at some stage of prebiotic life development proteins were not yet engaged in biochemical reactions and RNA carried out both the information storage task and the full range of catalytic roles necessary in primitive self-replicating systems. Here we report on the study of recombination reaction occuring between two 96 nucleotides (nts) fragments of RNAs under physiological...

  18. Experimental approaches to the measurement of dielectronic recombination

    International Nuclear Information System (INIS)

    In dielectronic recombination, the first step involves a continuum electron which excites a previously bound electron and, in so doing, loses just enough energy to be captured in a bound state (nl). This results in a doubly excited ion of a lower charge state which may either autoionize or emit a photon resulting in a stabilized recombination. The complete signature of the event is an ion of reduced charge and an emitted photon. Methods of measuring this event are discussed

  19. NOVEL PROCESSES AND PRODUCTS FOR RECOMBINANT PRODUCTION OF BIOPHARMACEUTICALS

    OpenAIRE

    Giuliani, Maria

    2009-01-01

    The monoclonal antibody market represents the fastest-growing segment within the biopharmaceutical industry (Evans and Das 2005). Indeed, recombinant antibodies and antibody fragments are widespread tools for research, diagnostics and therapy (Joosten et al., 2003). Large-scale production of recombinant antibodies and antibody fragments requires a suitable expression system which has to be cheap, accessible for genetic modifications, easily scaled up for greater demands and safe for use in co...

  20. Production of recombinant antibody fragments in Bacillus megaterium

    OpenAIRE

    Jahn Dieter; Schirrmann Thomas; Biedendieck Rebekka; Roth Andreas; Hust Michael; Jordan Eva; Dübel Stefan

    2007-01-01

    Abstract Background Recombinant antibodies are essential reagents for research, diagnostics and therapy. The well established production host Escherichia coli relies on the secretion into the periplasmic space for antibody synthesis. Due to the outer membrane of Gram-negative bacteria, only a fraction of this material reaches the medium. Recently, the Gram-positive bacterium Bacillus megaterium was shown to efficiently secrete recombinant proteins into the growth medium. Here we evaluated B. ...

  1. Recombinant mouse interferon-gamma regulation of antibody production.

    OpenAIRE

    Johnson, H M; Torres, B A

    1983-01-01

    Interferon-gamma produced in monkey cells by transfection with mouse interferon-gamma cDNA suppressed the mouse in vitro antibody response in a manner similar to that of natural mouse interferon-gamma. Significant suppression was obtained with as little as 1 U of interferon. Recombinant human interferon-gamma produced by cloning in a similar fashion was not suppressive. Both the suppressive and the antiviral activities of recombinant interferon-gamma were neutralized by antibodies to mouse na...

  2. Amifostine Metabolite WR-1065 Disrupts Homologous Recombination in Mammalian Cells

    OpenAIRE

    Dziegielewski, Jaroslaw; Goetz, Wilfried; Murley, Jeffrey S.; David J Grdina; Morgan, William F.; Janet E. Baulch

    2010-01-01

    Repair of DNA damage through homologous recombination (HR) pathways plays a crucial role in maintaining genome stability. However, overstimulation of HR pathways in response to genotoxic stress may abnormally elevate recombination frequencies, leading to increased mutation rates and delayed genomic instability. Radiation-induced genomic instability has been detected after exposure to both low- and high-linear energy transfer (LET) radiations, but the mechanisms responsible for initiating or p...

  3. Recombination Lines of CII in the Spectra of Planetary Nebulae

    OpenAIRE

    Sochi, Taha

    2010-01-01

    The current report presents the work to investigate the recombination lines of CII in the spectra of planetary nebulae. Two CIII targets were prepared and used to generate theoretical data required in the investigation of recombination lines that arise from collisions between electrons and ions in thin plasma found in planetary nebulae and other astrophysical objects. One of these targets contains 9 atomic terms while the other contains 26 terms. For each one of these targets, theoretical dat...

  4. Historical Perspectives Pertaining to the NIH Recombinant DNA Advisory Committee

    OpenAIRE

    Wivel, Nelson A.

    2014-01-01

    Science is host to a constantly emerging series of new paradigms, and it is this characteristic that makes science both interesting and dynamic. As a part of this continuum, it became possible to create recombinant DNA molecules. Immediately it was recognized that there was a potential for serious adverse events associated with this new technology. Following two scientific conferences at Asilomar, California, the National Institutes of Health moved quickly to create the Recombinant DNA Adviso...

  5. Prominent mitochondrial DNA recombination intermediates in human heart muscle

    OpenAIRE

    Kajander, Olli A; Karhunen, Pekka J.; Holt, Ian J.; Jacobs, Howard T.

    2001-01-01

    Recombination intermediates containing four-way (Holliday) junctions are generated during DNA repair and replication in many systems, including yeast mitochondrial DNA (mtDNA). In contrast, convincing evidence for recombination in mammalian mtDNA is lacking. We have used two-dimensional agarose-gel electrophoresis to analyse non-linear forms of mtDNA in human heart muscle. Replication intermediates from both the coupled and strand-asynchronous mtDNA replication pathways were detected. An addi...

  6. A Gateway MultiSite Recombination Cloning Toolkit

    OpenAIRE

    Petersen, Lena K.; Stowers, R. Steven

    2011-01-01

    The generation of DNA constructs is often a rate-limiting step in conducting biological experiments. Recombination cloning of single DNA fragments using the Gateway system provided an advance over traditional restriction enzyme cloning due to increases in efficiency and reliability. Here we introduce a series of entry clones and a destination vector for use in two, three, and four fragment Gateway MultiSite recombination cloning whose advantages include increased flexibility and versatility. ...

  7. DNA Cloning Using In Vitro Site-Specific Recombination

    OpenAIRE

    Hartley, James L.; Temple, Gary F.; Brasch, Michael A.

    2000-01-01

    As a result of numerous genome sequencing projects, large numbers of candidate open reading frames are being identified, many of which have no known function. Analysis of these genes typically involves the transfer of DNA segments into a variety of vector backgrounds for protein expression and functional analysis. We describe a method called recombinational cloning that uses in vitro site-specific recombination to accomplish the directional cloning of PCR products and the subsequent automatic...

  8. Multi-electron-recombination rates estimated within dense plasmas

    CERN Document Server

    Ziaja, B; Weckert, E

    2009-01-01

    We investigate the rates for multielectron recombination within a dense plasma environment in local thermodynamic equilibrium (LTE). We find that these multielectron recombination rates can be high within dense plasmas, and they should be treated in the simulations of the plasmas created by intense radiation, in particular for plasmas created by intense VUV radiation from free-electron-laser (FEL) or for modelling the inertial confinement fusion (ICF) plasmas.

  9. Multi-electron-recombination rates estimated within dense plasmas

    OpenAIRE

    Ziaja, B.; Wang, F.; Weckert, E.

    2008-01-01

    We investigate the rates for multielectron recombination within a dense plasma environment in local thermodynamic equilibrium (LTE). We find that these multielectron recombination rates can be high within dense plasmas, and they should be treated in the simulations of the plasmas created by intense radiation, in particular for plasmas created by intense VUV radiation from free-electron-laser (FEL) or for modelling the inertial confinement fusion (ICF) plasmas.

  10. Recombinant human migration inhibitory factor has adjuvant activity.

    OpenAIRE

    Weiser, W Y; Pozzi, L M; Titus, R G; David, J R

    1992-01-01

    Recombinant human migration inhibitory factor (MIF), isolated through functional expression cloning in COS-1 cells, up-regulates expression of genes encoding HLA-DR and interleukin 1 beta (IL-1 beta) and elaboration of IL-1 beta by human monocyte-derived macrophages. Administration of soluble bovine serum albumin or human immunodeficiency virus 120-kDa glycoprotein (HIV gp120) to mice in the presence of recombinant MIF together with incomplete Freund's adjuvant induced a strong T-cell prolife...

  11. The Time Scale of Recombination Rate Evolution in Great Apes.

    Science.gov (United States)

    Stevison, Laurie S; Woerner, August E; Kidd, Jeffrey M; Kelley, Joanna L; Veeramah, Krishna R; McManus, Kimberly F; Bustamante, Carlos D; Hammer, Michael F; Wall, Jeffrey D

    2016-04-01

    We present three linkage-disequilibrium (LD)-based recombination maps generated using whole-genome sequence data from 10 Nigerian chimpanzees, 13 bonobos, and 15 western gorillas, collected as part of the Great Ape Genome Project (Prado-Martinez J, et al. 2013. Great ape genetic diversity and population history. Nature 499:471-475). We also identified species-specific recombination hotspots in each group using a modified LDhot framework, which greatly improves statistical power to detect hotspots at varying strengths. We show that fewer hotspots are shared among chimpanzee subspecies than within human populations, further narrowing the time scale of complete hotspot turnover. Further, using species-specific PRDM9 sequences to predict potential binding sites (PBS), we show higher predicted PRDM9 binding in recombination hotspots as compared to matched cold spot regions in multiple great ape species, including at least one chimpanzee subspecies. We found that correlations between broad-scale recombination rates decline more rapidly than nucleotide divergence between species. We also compared the skew of recombination rates at centromeres and telomeres between species and show a skew from chromosome means extending as far as 10-15 Mb from chromosome ends. Further, we examined broad-scale recombination rate changes near a translocation in gorillas and found minimal differences as compared to other great ape species perhaps because the coordinates relative to the chromosome ends were unaffected. Finally, on the basis of multiple linear regression analysis, we found that various correlates of recombination rate persist throughout the African great apes including repeats, diversity, and divergence. Our study is the first to analyze within- and between-species genome-wide recombination rate variation in several close relatives. PMID:26671457

  12. KLL Dielectronic Recombination of Highly Charged Sulfur and Silicon Ions

    OpenAIRE

    Ali, Safdar

    2014-01-01

    Dielectronic recombination measurements for highly charged ions were performed at the Stockholm refrigerated electron beam ion trap. We have obtained KLL DR resonance strengths for highly charged H- and He-like sulfur and silicon ions. The experimental results are compared with the theoretical data obtained from GRASP II code. Both the experimental and calculated results agree well within the experimental error bars. Moreover, the dielectronic recombination resonance strengths are used to obt...

  13. Multiple biological activities of human recombinant interleukin 1.

    OpenAIRE

    Dinarello, C A; Cannon, J. G.; Mier, J W; Bernheim, H. A.; LoPreste, G; Lynn, D L; Love, R N; Webb, A C; Auron, P. E.; Reuben, R C

    1986-01-01

    Complementary DNA coding for human monocyte interleukin 1 (IL-1), pI 7 form, was expressed in Escherichia coli. During purification, IL-1 activity on murine T cells was associated with the recombinant protein. Homogeneous human recombinant IL-1 (hrIL-1) was tested in several assays to demonstrate the immunological and inflammatory properties attributed to this molecule. hrIL-1 induced proliferative responses in a cloned murine T cell in the presence of suboptimal concentrations of mitogen, wh...

  14. The next wave of recombinant and synthetic anticancer vaccines

    OpenAIRE

    Irvine, Kari R.; Restifo, Nicholas P

    1995-01-01

    The identification of tumor-associated antigens (TAA) recognized by T lymphocytes makes the development of antigen-specific synthetic and recombinant vaccines possible. The expression of TAA within a recombinant vector increases control over the kinetics and quantity, the molecular form, and the subcellular location of the immunogen delivered. The next generation of antitumor vaccines employs cytokines and costimulatory molecules expressed in concert with TAA that are capable of augmenting th...

  15. Recombination dramatically speeds up evolution of finite populations

    OpenAIRE

    Cohen, Elisheva; Kessler, David A.; Levine, Herbert

    2004-01-01

    We study the role of recombination, as practiced by genetically-competent bacteria, in speeding up Darwinian evolution. This is done by adding a new process to a previously-studied Markov model of evolution on a smooth fitness landscape; this new process allows alleles to be exchanged with those in the surrounding medium. Our results, both numerical and analytic, indicate that for a wide range of intermediate population sizes, recombination dramatically speeds up the evolutionary advance.

  16. Chimeragenesis of distantly-related proteins by noncontiguous recombination

    OpenAIRE

    Smith, Matthew A.; Romero, Philip A; Wu, Timothy; Brustad, Eric M.; Arnold, Frances H.

    2012-01-01

    We introduce a method for identifying elements of a protein structure that can be shuffled to make chimeric proteins from two or more homologous parents. Formulating recombination as a graph-partitioning problem allows us to identify noncontiguous segments of the sequence that should be inherited together in the progeny proteins. We demonstrate this noncontiguous recombination approach by constructing a chimera of β-glucosidases from two different kingdoms of life. Although the protein's alph...

  17. Fine-scale recombination and adaptive radiation could be linked.

    Science.gov (United States)

    Bodilis, Josselin

    2013-09-15

    The difficult reconstruction of the evolutionary history of the major surface protein gene oprF highlighted an adaptive radiation in the Pseudomonas fluorescens group. The recent work of Hao (2013) showed that partial recombination events in oprF gene occurred specifically in a P. fluorescens lineage under ecological niche segregation. So, I suggest that identification of lineage-specific fine-scale recombination may be a way to detect putative adaptive radiation in bacteria. PMID:23774687

  18. Wave function recombination instability in cold atom interferometers

    OpenAIRE

    Stickney, James A.; Zozulya, Alex A.

    2002-01-01

    Cold atom interferometers use guiding potentials that split the wave function of the Bose-Einstein condensate and then recombine it. We present theoretical analysis of the wave function recombination instability that is due to the weak nonlinearity of the condensate. It is most pronounced when the accumulated phase difference between the arms of the interferometer is close to an odd multiple of PI and consists in exponential amplification of the weak ground state mode by the strong first exci...

  19. Experimental observation of laser-stimulated radiative recombination

    International Nuclear Information System (INIS)

    Spontaneous radiative recombination between protons and electrons to form hydrogen atoms with 8≤n≤19 has been measured. CO2 laser light has been shown to induce stimulated radiative recombination to the n=11 and 12 levels with an inferred gain in the cross section of 1720±860 and 4790±2830 for a laser power of 12.6 and 15.3 W, respectively. This is in line with that predicted theoretically

  20. A Heritable Recombination System for Synthetic Darwinian Evolution in Yeast

    OpenAIRE

    Romanini, Dante W.; Peralta-Yahya, Pamela; Mondol, Vanessa; Cornish, Virginia W.

    2012-01-01

    Genetic recombination is central to the generation of molecular diversity and enhancement of evolutionary fitness in living systems. Methods such as DNA shuffling that recapitulate this diversity mechanism in vitro are powerful tools for engineering biomolecules with useful new functions by directed evolution. Synthetic biology now brings demand for analogous technologies that enable the controlled recombination of beneficial mutations in living cells. Thus, here we create a Heritable Recombi...

  1. Recombinant TCR ligand reverses clinical signs and CNS damage of EAE induced by recombinant human MOG.

    Science.gov (United States)

    Sinha, Sushmita; Subramanian, Sandhya; Emerson-Webber, Ashley; Lindner, Maren; Burrows, Gregory G; Grafe, Marjorie; Linington, Christopher; Vandenbark, Arthur A; Bernard, Claude C A; Offner, Halina

    2010-06-01

    Increasing evidence suggests that in addition to T cell-dependent effector mechanisms, autoantibodies are also involved in the pathogenesis of MS, including demyelinating antibodies specific for myelin oligodendrocyte glycoprotein (MOG). Our previous studies have demonstrated that recombinant T cell receptor ligands (RTLs) are very effective for treating T cell-mediated experimental autoimmune encephalomyelitis (EAE). In order to expand the scope of RTL therapy in MS patients, it was of interest to study RTL treatment of EAE involving a demyelinating antibody component. Therefore, we evaluated the therapeutic effects of RTL551, specific for T cells reactive to mouse (m)MOG-35-55 peptide, on EAE induced with recombinant human (rh)MOG in C57BL/6 mice. We report that RTL551 therapy can reverse disease progression and reduce demyelination and axonal damage induced by rhMOG without suppressing the anti-MOG antibody response. This result suggests that T cell-mediated inflammation and associated blood-brain barrier dysfunction are the central contributors to EAE pathogenesis and that successful regulation of these key players restricts potential damage by demyelinating antibodies. The results of our study lend support for the use of RTL therapy for treatment of MS subjects whose disease includes inflammatory T cells as well as those with an additional antibody component. PMID:19789980

  2. Collision and recombination driven instabilities in variable charged dusty plasmas

    Indian Academy of Sciences (India)

    S Bal; M Bose

    2013-04-01

    The dust-acoustic instability driven by recombination of electrons and ions on the surface of charged and variably-charged dust grains as well as by collisions in dusty plasmas with significant pressure of background neutrals have been theoretically investigated. The recombination driven instability is shown to be dominant in the long wavelength regime even in the presence of dust-neutral and ion-neutral collisions, while in the shorter wavelength regime, the dust-neutral collision is found to play a major role. In an earlier research work, the dust-neutral collision was neglected in comparison to the effect due to the recombination for estimating the dust-acoustic instability; later the other report shows that the recombination effect is negligible in the presence of dust-neutral collisions. In line of this present situation our investigation revealed that the recombination is more important than dust-neutral collisions in laboratory plasma and fusion plasma, while the dust-neutral collision frequency is dominant in the interstellar plasmas. The effects of ion and dust densities and ion streaming on the recombination and collision driven mode in parameter regimes relevant for many experimental studies on dusty plasmas have also been calculated.

  3. Mathematical model for aerobic culture of a recombinant yeast

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.; Scharer, J.M.; Moo-Young, M. [Waterloo Univ., ON (Canada). Dept. of Chemical Engineering

    1997-09-01

    A mathematical model was formulated to simulate cell growth, plasmid loss and recombinant protein production during the aerobic culture of a recombinant yeast S. cerevisiae. Model development was based on three simplified metabolic events in the yeast: glucose fermentation, glucose oxidation and ethanol oxidation. Cell growth was expressed as a composite of these metabolic events. Their contributions to the total specific growth rate depended on the activities of the pacemaker enzyme pools of the individual pathways. The pacemaker enzyme pools were regulated by the specific glucose uptake rate. The effect of substrate concentrations on the specific growth rate was described by a modified Monod equation. It was assumed that recombinant protein formation is only associated with oxidative pathways. Plasmid loss kinetics was formulated based on segregational instability during cell division by assuming constant probability of plasmid loss. Experiments on batch fermentation of recombinant S. cerevisiae C468/pGAC9 (ATCC 20690), which expresses Aspergillus awamori glucoamylase gene and secretes glucoamylase into the extracellular medium, were carried out in an airlift bioreactor in order to evaluate the proposed model. The model successfully predicted the dynamics of cell growth, glucose consumption, ethanol metabolism, glucoamylase production and plasmid instability. Excellent agreement between model simulations and our experimental data was achieved. Using published experimental data, model agreement was also found for other recombinant yeast strains. In general, the proposed model appears to be useful for the design, scale-up, control and optimization of recombinant yeast bioprocesses. (orig.) With 3 figs., 1 tab., 15 refs.

  4. Recombinant medaka (Oryzias melastigmus) pro-hepcidin: Multifunctional characterization.

    Science.gov (United States)

    Cai, Ling; Cai, Jing-Jing; Liu, Hai-Peng; Fan, Dan-Qing; Peng, Hui; Wang, Ke-Jian

    2012-02-01

    Recently, two hepcidin variant genes (Om-hep1 and Om-hep2) were identified in a model fish marine medaka and both were highly induced in vivo with bacterial challenge, suggesting that the medaka hepcidin may have a similar function to other reported teleostean hepcidins. In the present study, the antibacterial, antiviral and antitumor activities of Om-hep1 were determined using its synthetic and recombinant pro-peptides. The recombinant pro-hepcidin1 was expressed in Escherichia coli and an effective method to produce recombinant Pro-Omhep1 was developed in order to obtain a right folded structure. The results showed that both the synthetic mature peptide and recombinant pro-peptide had similar antibacterial activity against Gram-positive and negative bacteria. In particular, both the synthetic mature Om-hep1 and recombinant Pro-Omhep1 inhibited the viral replication of white spot syndrome virus in the hematopoietic tissue cells of the crayfish Cherax quadricarinatus. Om-hep1 also presented antitumor activity on the cultured human hepatocellular carcinoma cells. In addition, the antimicrobial mechanism of Om-hep1 was measured and it was found that Om-hep1 was likely to be non-membranolytic. The recombinant Pro-Omhep1 performed better biological activity compared to the synthetic mature Om-hep1. This study suggested that Om-hep1 was likely to be an important multifunction protein involved in various resistance actions in the marine medaka immune system. PMID:22051539

  5. Genetic characterization of somatic recombination in Trichoderma pseudokoningii

    Directory of Open Access Journals (Sweden)

    Barcellos Fernando Gomes

    2003-01-01

    Full Text Available Crossing experiments via hyphal anastomosis between two strains contrasting for auxotrophic markers of Trichoderma pseudokoningii were conducted to characterize the somatic recombination process in this specie. Four crossings were made and a total of 1052 colonies obtained from conidial suspensions of the heterokaryotic colonies were analyzed. Sixty-eight recombinant colonies, from four growing generations, were analyzed for the auxotrophic markers. Of the 68 colonies analyzed, 58 were stable after four generations and the remainders were unstable, reverting to one of the parentals. Most of the recombinant colonies were unstable through subculture and after four growing generations they showed the leu ino met markers (auxotrophic for leucin, inositol and metionin respectively. The unstable recombinant colonies showed irregular growing borders, sparse sporulation and frequent sector formation. The results suggest the occurrence of recombination mechanisms in the heterokaryon (somatic recombination, different from those described for the parasexual cycle or parameiosis. Therefore, we proposed the ocurrence of nuclei degradation from one parental (non prevalent parental in the heterokaryon and that the resulting chromosomal fragments may be incorporated into whole nuclei of the another parental (prevalent parental. However the parameiosis as originally described cannot be excluded.

  6. RPA homologs and ssDNA processing during meiotic recombination.

    Science.gov (United States)

    Ribeiro, Jonathan; Abby, Emilie; Livera, Gabriel; Martini, Emmanuelle

    2016-06-01

    Meiotic homologous recombination is a specialized process that involves homologous chromosome pairing and strand exchange to guarantee proper chromosome segregation and genetic diversity. The formation and repair of DNA double-strand breaks (DSBs) during meiotic recombination differs from those during mitotic recombination in that the homologous chromosome rather than the sister chromatid is the preferred repair template. The processing of single-stranded DNA (ssDNA) formed on intermediate recombination structures is central to driving the specific outcomes of DSB repair during meiosis. Replication protein A (RPA) is the main ssDNA-binding protein complex involved in DNA metabolism. However, the existence of RPA orthologs in plants and the recent discovery of meiosis specific with OB domains (MEIOB), a widely conserved meiosis-specific RPA1 paralog, strongly suggest that multiple RPA complexes evolved and specialized to subdivide their roles during DNA metabolism. Here we review ssDNA formation and maturation during mitotic and meiotic recombination underlying the meiotic specific features. We describe and discuss the existence and properties of MEIOB and multiple RPA subunits in plants and highlight how they can provide meiosis-specific fates to ssDNA processing during homologous recombination. Understanding the functions of these RPA homologs and how they interact with the canonical RPA subunits is of major interest in the fields of meiosis and DNA repair. PMID:26520106

  7. Immunoglobulin/Myc recombinations in murine Peyer's patch follicles.

    Science.gov (United States)

    Müller, J R; Mushinski, E B; Williams, J A; Hausner, P F

    1997-09-01

    Immunoglobulin heavy chain (Igh)/Myc recombinations are a hallmark of pristane-induced mouse plasmacytomas but are also frequently found in non-tumorous tissues. Here we describe for the first time a PCR-based technique for detecting fusions between Igh mu or Igh alpha and Myc in situ. Igh/Myc recombinations were found in transplanted and primary plasmacytomas. In addition, the gut-associated lymphoid tissues of plasmacytoma-free BALB/c mice were investigated for the presence of Igh/Myc fusions. Igh/Myc rearrangements were detected in Peyer's patch follicles and in the intestinal lamina propria both in normal mice and in mice shortly after pristane treatment. The sequence analysis showed that i) three to five different Igh/Myc hybrid sequences were present in individual follicles, ii) Igh/Myc recombinations can be subjected to additional switch recombinations as shown by related sequences in neighboring cells, and iii) cells harboring these rearrangements migrate into the adjacent lamina propria. The results indicate that Peyer's patches are a hyper-recombinogenic tissue. Myc recombination-positive cells are present in at least 100-fold more frequently than expected if recombinations were random, which suggests that this kind of trans-chromosomal rearrangement may be targeted. PMID:9290947

  8. Enhanced defects recombination in ion irradiated SiC

    Energy Technology Data Exchange (ETDEWEB)

    Izzo, G. [Department of Physics and Astronomy, Catania University, Via S. Sofia 64, 95123 Catania (Italy); Litrico, G., E-mail: grazia.litrico@ct.infn.i [Department of Physics and Astronomy, Catania University, Via S. Sofia 64, 95123 Catania (Italy); Grassia, F.; Calcagno, L.; Foti, G. [Department of Physics and Astronomy, Catania University, Via S. Sofia 64, 95123 Catania (Italy)

    2010-10-01

    Point defects induced in SiC by ion irradiation show a recombination at temperatures as low as 320 K and this process is enhanced after running current density ranging from 80 to 120 A/cm{sup 2}. Ion irradiation induces in SiC the formation of different defect levels and low-temperature annealing changes their concentration. Some levels (S{sub 0}, S{sub x} and S{sub 2}) show a recombination and simultaneously a new level (S{sub 1}) is formed. An enhanced recombination of defects is besides observed after running current in the diode at room temperature. The carriers introduction reduces the S{sub 2} trap concentration, while the remaining levels are not modified. The recombination is negligible up to a current density of 50 A/cm{sup 2} and increases at higher current density. The enhanced recombination of the S{sub 2} trap occurs at 300 K, which otherwise requires a 400 K annealing temperature. The process can be related to the electron-hole recombination at the associated defect.

  9. Homologous recombination in DNA repair and DNA damage tolerance

    Institute of Scientific and Technical Information of China (English)

    Xuan Li; Wolf-Dietrich Heyer

    2008-01-01

    Homologous recombination (HR) comprises a series of interrelated pathways that function in the repair of DNA double-stranded breaks (DSBs) and interstrand crosslinks (ICLs). In addition, recombination provides critical sup-port for DNA replication in the recovery of stalled or broken replication forks, contributing to tolerance of DNA damage. A central core of proteins, most critically the RecA homolog Rad51, catalyzes the key reactions that typify HR: homology search and DNA strand invasion. The diverse functions of recombination are reflected in the need for context-specific factors that perform supplemental functions in conjunction with the core proteins. The inability to properly repair complex DNA damage and resolve DNA replication stress leads to genomic instability and contributes to cancer etiology. Mutations in the BRCA2 recombination gene cause predisposition to breast and ovarian cancer as well as Fanconi anemia, a cancer predisposition syndrome characterized by a defect in the repair of DNA interstrand crosslinks. The cellular functions of recombination are also germane to DNA-based treatment modaUties of cancer, which target replicating cells by the direct or indirect induction of DNA lesions that are substrates for recombination pathways. This review focuses on mechanistic aspects of HR relating to DSB and ICL repair as well as replication fork support.

  10. Similarity of recombinant human perlecan domain 1 by alternative expression systems bioactive heterogenous recombinant human perlecan D1

    DEFF Research Database (Denmark)

    Ellis, April L; Pan, Wensheng; Yang, Guang;

    2010-01-01

    perlecan domain 1 (HSPG2 abbreviated as rhPln.D1) synthesized in either HEK 293 cells or HUVECs by transient gene delivery using either adenoviral or expression plasmid technology. RESULTS: By SDS-PAGE analysis following anion exchange chromatography, the recombinant proteoglycans appeared to possess......-based therapeutics, we have shown here that proteoglycan synthesis, in different cell lines where GAG profiles typically differ, can be directed by recombinant technology to produce populations of bioactive recombinants with highly similar GAG profiles.......BACKGROUND: Heparan sulfate glycosaminoglycans are diverse components of certain proteoglycans and are known to interact with growth factors as a co-receptor necessary to induce signalling and growth factor activity. In this report we characterize heterogeneously glycosylated recombinant human...

  11. Differential requirements of singleplex and multiplex recombineering of large DNA constructs.

    Directory of Open Access Journals (Sweden)

    Thimma R Reddy

    Full Text Available Recombineering is an in vivo genetic engineering technique involving homologous recombination mediated by phage recombination proteins. The use of recombineering methodology is not limited by size and sequence constraints and therefore has enabled the streamlined construction of bacterial strains and multi-component plasmids. Recombineering applications commonly utilize singleplex strategies and the parameters are extensively tested. However, singleplex recombineering is not suitable for the modification of several loci in genome recoding and strain engineering exercises, which requires a multiplex recombineering design. Defining the main parameters affecting multiplex efficiency especially the insertion of multiple large genes is necessary to enable efficient large-scale modification of the genome. Here, we have tested different recombineering operational parameters of the lambda phage Red recombination system and compared singleplex and multiplex recombineering of large gene sized DNA cassettes. We have found that optimal multiplex recombination required long homology lengths in excess of 120 bp. However, efficient multiplexing was possible with only 60 bp of homology. Multiplex recombination was more limited by lower amounts of DNA than singleplex recombineering and was greatly enhanced by use of phosphorothioate protection of DNA. Exploring the mechanism of multiplexing revealed that efficient recombination required co-selection of an antibiotic marker and the presence of all three Red proteins. Building on these results, we substantially increased multiplex efficiency using an ExoVII deletion strain. Our findings elucidate key differences between singleplex and multiplex recombineering and provide important clues for further improving multiplex recombination efficiency.

  12. Effects of the rad52 gene on recombination in Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Effects of the rad52 mutation in Saccharomyces cerevisiae on meiotic, γ-ray-induced, uv-induced, and spontaneous mitotic recombination were studied. The rad52/rad52 diploids undergo premeiotic DNA synthesis; sporulation occurs but inviable spores are produced. Intra- and intergenic recombination during meiosis were examined in cells transferred from sporulation medium to vegetative medium at different time intervals. No intragenic recombination was observed at the hisl-1/hisl-315 and trp5-2/trp5-48 heteroalleles. Gene-centromere recombination was also not observed in rad52/rad52 diploids. No γ-ray-induced intragenic mitotic recombination is seen in rad52/rad52 diploids and uv-induced intragenic recombination is greatly reduced. However, spontaneous mitotic recombination is not similarly affected. The RAD52 gene thus functions in recombination in meiosis and in γ-ray and uv-induced mitotic recombination but not in spontaneous mitotic recombination

  13. Clinical significance on changes of platelet aggregation test, von Willebrand factor,antithrombin and D-dimer assayin acute cerebral infarction patients%急性脑梗死患者血小板聚集功能、血管性血友病因子、抗凝血酶及 D-二聚体测定的临床意义

    Institute of Scientific and Technical Information of China (English)

    叶青跃; 程鹏飞; 周有利; 饶汉武; 黄承芳; 周立

    2015-01-01

    目的:探讨急性脑梗死患者血小板聚集功能( PAgT)、血管性血友病因子( vWF)、抗凝血酶( AT)和D-二聚体( D-dimer)水平变化及临床意义。方法选用相应的方法和仪器测定112例脑梗死及80例健康对照者血(浆) PAgT、vWF、AT和D-dimer水平变化,同时对部分患者进行治疗前、后的对比分析。结果脑梗死患者血中PAgT、vWF、D-dimer等指标均明显高于健康对照组,AT活性较对照组显著降低,差异有统计学意义(P<0.05或P<0.01)。选取经治疗效果明显好转的78例脑梗死患者,出院前取空腹静脉血测定PAgT、vWF、AT、D-dimer等指标,并与治疗前对照,结果治疗后PAgT、vWF、D-dimer降低,AT活性升高,差异有统计学意义(P<0.05或P<0.01)。结论脑梗死患者体内存在明显的凝血及纤溶功能异常,与血管内皮损伤、血小板聚集功能增强、凝血及纤溶功能亢进、抗凝功能降低等多因素有关。 PAgT、vWF、AT、D-dimer可以作为脑梗死患者诊断、治疗监测和预后判断的参考指标。%Objective To evaluate the clinical signification of coagulation ,anti-coagulation and fibrinolysis indexes i.e.platelet aggrega-tion test(PAgT),von Willebrand factor(vWF),antithrombin(AT),D-dimer in acute cerebral infarction patients.Methods vWF was as-sayed using ELISA method,AT was determined by chromogenic substances assay,and Latex enhanced immune turbidimetry for D-dimer. vWF,AT and D-dimer all the parameters were finished by SysmexCA-7000 automated blood coagulation analyzer.PAgT was measured sim-ultaneously using a whole-blood Lumi-Aggregometer by CHRMNO-LOG platelet aggregation apparatus.Results PAgT, vWF, D-dimer were significantly higher in acute cerebral infarction patients group,compared with those in the control group(P<0.05 or P<0.01). while AT was significantly lower(P<0.05).After effective treatment,PAgT,vWF,AT,D-dimer Indicators are all

  14. Transforming the treatment for hemophilia B patients: update on the clinical development of recombinant fusion protein linking recombinant coagulation factor IX with recombinant albumin (rIX-FP).

    Science.gov (United States)

    Santagostino, Elena

    2016-05-01

    Recombinant fusion protein linking recombinant coagulation factor IX with recombinant albumin (rIX-FP; Idelvion®(†)) is an innovative new treatment designed to extend the half-life of factor IX (FIX) and ease the burden of care for hemophilia B patients. The rIX-FP clinical development program - PROLONG-9FP - is in its advanced phases, with pivotal studies in previously treated adults, adolescents, and pediatrics now completed. Across all age groups studied, rIX-FP has demonstrated a markedly improved pharmacokinetic profile compared with plasma-derived and recombinant FIX treatments, with a 30-40% higher incremental recovery, an approximately 5-fold longer half-life, a lower clearance, and a greater area under the curve. rIX-FP has been very well tolerated with an excellent safety profile. In the pivotal studies, there have been no reports of FIX inhibitors or antidrug antibodies, and few treatment-related adverse events have been observed. Prophylactic regimens of rIX-FP administered once weekly to once every 14 days have been highly effective. When used for surgical prophylaxis, a single infusion of rIX-FP has been sufficient to maintain hemostasis, even during major orthopedic surgery. An ongoing study is now enrolling previously untreated patients and evaluating the possibility of extending the dosing interval to every 21 days. There is little doubt that rIX-FP will transform the treatment of hemophilia B. PMID:27288064

  15. Modelling of the operational behaviour of passive autocatalytic recombiners

    International Nuclear Information System (INIS)

    Due to severe accidents in nuclear power plants, a significant amount of hydrogen can be produced. In pressurized water reactors, a possible and wide-spread measurement is the use of auto-catalytic recombiners. There are numerous numerical models describing the operational behaviour of recombiners for containment codes. The numerical model REKO-DIREKT was developed at the Forschungszentrum Juelich. This model describes the chemical reaction on the catalytic sheets by a physical model, as opposed to the usual codes based on empirical correlations. Additionally, there have been experimental studies concerning the catalytic recombination of hydrogen since the 1990s. The aim of this work is the further development of the program REKO-DIREKT to an independent recombiner model for severe accident and containment codes. Therefore, the catalyst model already existed has been submitted by a parameter optimization with an experimental database expanded during this work. In addition, a chimney model has been implemented which allows the calculation of the free convection flow through the recombiner housing due to the exothermal reaction. This model has been tested by experimental data gained by a recently built test facility. The complete recombiner model REKO-DIREKT has been validated by data from literature. Another aim of this work is the derivation of the reaction kinetics for recombiner designs regarding future reactor concepts. Therefore, experimental studies both on single catalytic coated meshes as well as on two meshes installed in a row have been performed in laboratory scale. By means of the measured data, a theoretical approach for the determination of the reaction rate has been derived.

  16. Replication and recombination in adenovirus-infected cells are temporally and functionally related.

    OpenAIRE

    Young, C S; Cachianes, G; Munz, P; Silverstein, S.(Department of Physics, Stockholm University, Stockholm, Sweden)

    1984-01-01

    We have studied the temporal and functional relationships between DNA replication and recombination in adenovirus-infected cells by using Southern blot hybridization to detect recombinant products among intracellular viral genomes. The data show that recombination can be detected soon after DNA replication has commenced and that the proportion of recombinant products increases thereafter. To determine the functional relationship between DNA replication and recombination, replication was block...

  17. Enhanced levels of λ Red-mediated recombinants in mismatch repair mutants

    OpenAIRE

    Costantino, Nina; Court, Donald L.

    2003-01-01

    Homologous recombination can be used to generate recombinants on episomes or directly on the Escherichia coli chromosome with PCR products or synthetic single-stranded DNA (ssDNA) oligonucleotides (oligos). Such recombination is possible because bacteriophage λ-encoded functions, called Red, efficiently recombine linear DNA with homologies as short as 20–70 bases. This technology, termed recombineering, provides ways to modify genes and segments of the chromosome as well as to study homologou...

  18. A Functional Analysis of the Spacer of V(D)J Recombination Signal Sequences

    OpenAIRE

    Lee Alfred Ian; Fugmann Sebastian D; Cowell Lindsay G; Ptaszek Leon M; Kelsoe Garnett; Schatz David G

    2003-01-01

    During lymphocyte development, V(D)J recombination assembles antigen receptor genes from component V, D, and J gene segments. These gene segments are flanked by a recombination signal sequence (RSS), which serves as the binding site for the recombination machinery. The murine Jbeta2.6 gene segment is a recombinationally inactive pseudogene, but examination of its RSS reveals no obvious reason for its failure to recombine. Mutagenesis of the Jbeta2.6 RSS demonstrates that the sequences of the ...

  19. Patterns of Recombination in HIV-1M Are Influenced by Selection Disfavouring the Survival of Recombinants with Disrupted Genomic RNA and Protein Structures

    OpenAIRE

    Golden, Michael; Muhire, Brejnev M.; Semegni, Yves; Martin, Darren P.

    2014-01-01

    Genetic recombination is a major contributor to the ongoing diversification of HIV. It is clearly apparent that across the HIV-genome there are defined recombination hot and cold spots which tend to co-localise both with genomic secondary structures and with either inter-gene boundaries or intra-gene domain boundaries. There is also good evidence that most recombination breakpoints that are detectable within the genes of natural HIV recombinants are likely to be minimally disruptive of intra-...

  20. Genome-wide recombination dynamics are associated with phenotypic variation in maize.

    Science.gov (United States)

    Pan, Qingchun; Li, Lin; Yang, Xiaohong; Tong, Hao; Xu, Shutu; Li, Zhigang; Li, Weiya; Muehlbauer, Gary J; Li, Jiansheng; Yan, Jianbing

    2016-05-01

    Meiotic recombination is a major driver of genetic diversity, species evolution, and agricultural improvement. Thus, an understanding of the genetic recombination landscape across the maize (Zea mays) genome will provide insight and tools for further study of maize evolution and improvement. Here, we used c. 50 000 single nucleotide polymorphisms to precisely map recombination events in 12 artificial maize segregating populations. We observed substantial variation in the recombination frequency and distribution along the ten maize chromosomes among the 12 populations and identified 143 recombination hot regions. Recombination breakpoints were partitioned into intragenic and intergenic events. Interestingly, an increase in the number of genes containing recombination events was accompanied by a decrease in the number of recombination events per gene. This kept the overall number of intragenic recombination events nearly invariable in a given population, suggesting that the recombination variation observed among populations was largely attributed to intergenic recombination. However, significant associations between intragenic recombination events and variation in gene expression and agronomic traits were observed, suggesting potential roles for intragenic recombination in plant phenotypic diversity. Our results provide a comprehensive view of the maize recombination landscape, and show an association between recombination, gene expression and phenotypic variation, which may enhance crop genetic improvement. PMID:26720856

  1. High frequency of microsatellites in S. cerevisiae meiotic recombination hotspots

    Directory of Open Access Journals (Sweden)

    Pitt Joel PW

    2008-01-01

    Full Text Available Abstract Background Microsatellites are highly abundant in eukaryotic genomes but their function and evolution are not yet well understood. Their elevated mutation rate makes them ideal markers of genetic difference, but high levels of unexplained heterogeneity in mutation rates among microsatellites at different genomic locations need to be elucidated in order to improve the power and accuracy of the many types of study that use them as genetic markers. Recombination could contribute to this heterogeneity, since while replication errors are thought to be the predominant mechanism for microsatellite mutation, meiotic recombination is involved in some mutation events. There is also evidence suggesting that microsatellites could function as recombination signals. The yeast S. cerevisiae is a useful model organism with which to further explore the link between microsatellites and recombination, since it is very amenable to genetic study, and meiotic recombination hotspots have been mapped throughout its entire genome. Results We examined in detail the relationship between microsatellites and hotspots of meiotic double-strand breaks, the precursors of meiotic recombination, throughout the S. cerevisiae genome. We included all tandem repeats with motif length (repeat period between one and six base pairs. Long, short and two-copy arrays were considered separately. We found that long, mono-, di- and trinucleotide microsatellites are around twice as frequent in hot than non-hot intergenic regions. The associations are weak or absent for repeats with less than six copies, and also for microsatellites with 4–6 base pair motifs, but high-copy arrays with motif length greater than three are relatively very rare throughout the genome. We present evidence that the association between high-copy, short-motif microsatellites and recombination hotspots is not driven by effects on microsatellite distribution of other factors previously linked to both

  2. Patterns of recombination in HIV-1M are influenced by selection disfavouring the survival of recombinants with disrupted genomic RNA and protein structures.

    Directory of Open Access Journals (Sweden)

    Michael Golden

    Full Text Available Genetic recombination is a major contributor to the ongoing diversification of HIV. It is clearly apparent that across the HIV-genome there are defined recombination hot and cold spots which tend to co-localise both with genomic secondary structures and with either inter-gene boundaries or intra-gene domain boundaries. There is also good evidence that most recombination breakpoints that are detectable within the genes of natural HIV recombinants are likely to be minimally disruptive of intra-protein amino acid contacts and that these breakpoints should therefore have little impact on protein folding. Here we further investigate the impact on patterns of genetic recombination in HIV of selection favouring the maintenance of functional RNA and protein structures. We confirm that chimaeric Gag p24, reverse transcriptase, integrase, gp120 and Nef proteins that are expressed by natural HIV-1 recombinants have significantly lower degrees of predicted folding disruption than randomly generated recombinants. Similarly, we use a novel single-stranded RNA folding disruption test to show that there is significant, albeit weak, evidence that natural HIV recombinants tend to have genomic secondary structures that more closely resemble parental structures than do randomly generated recombinants. These results are consistent with the hypothesis that natural selection has acted both in the short term to purge recombinants with disrupted RNA and protein folds, and in the longer term to modify the genome architecture of HIV to ensure that recombination prone sites correspond with those where recombination will be minimally deleterious.

  3. CRISPR-Cas9-assisted recombineering in Lactobacillus reuteri.

    Science.gov (United States)

    Oh, Jee-Hwan; van Pijkeren, Jan-Peter

    2014-01-01

    Clustered regularly interspaced palindromic repeats (CRISPRs) and the CRISPR-associated (Cas) nuclease protect bacteria and archeae from foreign DNA by site-specific cleavage of incoming DNA. Type-II CRISPR-Cas systems, such as the Streptococcus pyogenes CRISPR-Cas9 system, can be adapted such that Cas9 can be guided to a user-defined site in the chromosome to introduce double-stranded breaks. Here we have developed and optimized CRISPR-Cas9 function in the lactic acid bacterium Lactobacillus reuteri ATCC PTA 6475. We established proof-of-concept showing that CRISPR-Cas9 selection combined with single-stranded DNA (ssDNA) recombineering is a realistic approach to identify at high efficiencies edited cells in a lactic acid bacterium. We show for three independent targets that subtle changes in the bacterial genome can be recovered at efficiencies ranging from 90 to 100%. By combining CRISPR-Cas9 and recombineering, we successfully applied codon saturation mutagenesis in the L. reuteri chromosome. Also, CRISPR-Cas9 selection is critical to identify low-efficiency events such as oligonucleotide-mediated chromosome deletions. This also means that CRISPR-Cas9 selection will allow identification of recombinant cells in bacteria with low recombineering efficiencies, eliminating the need for ssDNA recombineering optimization procedures. We envision that CRISPR-Cas genome editing has the potential to change the landscape of genome editing in lactic acid bacteria, and other Gram-positive bacteria. PMID:25074379

  4. Recombination Phenotypes of Escherichia coli greA Mutants

    Directory of Open Access Journals (Sweden)

    Poteete Anthony R

    2011-03-01

    Full Text Available Abstract Background The elongation factor GreA binds to RNA polymerase and modulates transcriptional pausing. Some recent research suggests that the primary role of GreA may not be to regulate gene expression, but rather, to promote the progression of replication forks which collide with RNA polymerase, and which might otherwise collapse. Replication fork collapse is known to generate dsDNA breaks, which can be recombinogenic. It follows that GreA malfunction could have consequences affecting homologous recombination. Results Escherichia coli mutants bearing substitutions of the active site acidic residues of the transcription elongation factor GreA, D41N and E44K, were isolated as suppressors of growth inhibition by a toxic variant of the bacteriophage lambda Red-beta recombination protein. These mutants, as well as a D41A greA mutant and a greA deletion, were tested for proficiency in recombination events. The mutations were found to increase the efficiency of RecA-RecBCD-mediated and RecA-Red-mediated recombination, which are replication-independent, and to decrease the efficiency of replication-dependent Red-mediated recombination. Conclusion These observations provide new evidence for a role of GreA in resolving conflicts between replication and transcription.

  5. Suppression of auger recombination in ""giant"" core/shell nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Santamaria, Florencio [Los Alamos National Laboratory; Vela, Javier [Los Alamos National Laboratory; Schaller, Richard D [Los Alamos National Laboratory; Hollingsworth, Jennifer A [Los Alamos National Laboratory; Klimov, Victor I [Los Alamos National Laboratory; Chen, Yongfen [NON LANL

    2009-01-01

    Many potential applications of semiconductor nanocrystals are hindered by nonradiative Auger recombination wherein the electron-hole (exciton) recombination energy is transferred to a third charge carrier. This process severely limits the lifetime and bandwidth of optical gain, leads to large nonradiative losses in light emitting diodes and photovoltaic cells, and is believed to be responsible for intermittency ('blinking') of emission from single nanocrystals. The development of nanostructures in which Auger recombination is suppressed has been a longstanding goal in colloidal nanocrystal research. Here, we demonstrate that such suppression is possible using so-called 'giant' nanocrystals that consist of a small CdSe core and a thick CdS shell. These nanostructures exhibit a very long biexciton lifetime ({approx}10 ns) that is likely dominated by radiative decay instead of non-radiative Auger recombination. As a result of suppressed Auger recombination, even high-order multiexcitons exhibit high emission efficiencies, which allows us to demonstrate optical amplification with an extraordinarily large bandwidth (>500 me V) and record low excitation thresholds.

  6. In vivo metabolism of recombinant human erythropoietin in the rat

    Energy Technology Data Exchange (ETDEWEB)

    Spivak, J.L.; Hogans, B.B.

    1989-01-01

    We compared the in vivo plasma clearance and organ accumulation in anesthetized rats of 125I-labeled, recombinant human erythropoietin and 125I-labeled, desialylated recombinant erythropoietin. The immediate volume of distribution of 125I-labeled, recombinant erythropoietin approximated that of the plasma volume. Its plasma clearance was multiexponential, with an initial rapid distribution phase (t1/2 = 53 minutes) and a slower elimination phase (t1/2 = 180 minutes). Organ accumulation of labeled recombinant erythropoietin, as compared with 125I-labeled human albumin, was negligible until 30 minutes after injection when small amounts appeared in the kidneys and bone marrow. Only 24% of the 125I-labeled, desialylated recombinant erythropoietin was recovered immediately after injection, and 96% of the hormone was cleared from the plasma with a t1/2 of 2.0 minutes. The bulk of the desialylated hormone accumulated in the liver where it was rapidly catabolized and its breakdown products released back into the plasma. Significantly, in contrast to unmodified erythropoietin, there was also early accumulation of desialylated hormone in the kidneys, marrow, and spleen. Desialylated orosomucoid but not orosomucoid, yeast mannan, or dextran sulfate 500 inhibited the rapid plasma clearance and hepatic accumulation of desialylated erythropoietin. Oxidation of the desialylated hormone restored its plasma recovery and clearance to normal but rendered it biologically inactive, and accumulation in organs other than the kidney was negligible.

  7. Recombinant host cells and media for ethanol production

    Science.gov (United States)

    Wood, Brent E; Ingram, Lonnie O; Yomano, Lorraine P; York, Sean W

    2014-02-18

    Disclosed are recombinant host cells suitable for degrading an oligosaccharide that have been optimized for growth and production of high yields of ethanol, and methods of making and using these cells. The invention further provides minimal media comprising urea-like compounds for economical production of ethanol by recombinant microorganisms. Recombinant host cells in accordance with the invention are modified by gene mutation to eliminate genes responsible for the production of unwanted products other than ethanol, thereby increasing the yield of ethanol produced from the oligosaccharides, relative to unmutated parent strains. The new and improved strains of recombinant bacteria are capable of superior ethanol productivity and yield when grown under conditions suitable for fermentation in minimal growth media containing inexpensive reagents. Systems optimized for ethanol production combine a selected optimized minimal medium with a recombinant host cell optimized for use in the selected medium. Preferred systems are suitable for efficient ethanol production by simultaneous saccharification and fermentation (SSF) using lignocellulose as an oligosaccharide source. The invention also provides novel isolated polynucleotide sequences, polypeptide sequences, vectors and antibodies.

  8. Temporally-controlled site-specific recombination in zebrafish.

    Directory of Open Access Journals (Sweden)

    Stefan Hans

    Full Text Available Conventional use of the site-specific recombinase Cre is a powerful technology in mouse, but almost absent in other vertebrate model organisms. In zebrafish, Cre-mediated recombination efficiency was previously very low. Here we show that using transposon-mediated transgenesis, Cre is in fact highly efficient in this organism. Furthermore, temporal control of recombination can be achieved by using the ligand-inducible CreER(T2. Site-specific recombination only occurs upon administration of the drug tamoxifen (TAM or its active metabolite, 4-hydroxy-tamoxifen (4-OHT. Cre-mediated recombination is detectable already 4 or 2 hours after administration of TAM or 4-OHT, demonstrating fast recombination kinetics. In addition, low doses of TAM allow mosaic labeling of single cells. Combined, our results show that conditional Cre/lox will be a valuable tool for both, embryonic and adult zebrafish studies. Furthermore, single copy insertion transgenesis of Cre/lox constructs suggest a strategy suitable also for other organisms.

  9. Recombination spot identification Based on gapped k-mers.

    Science.gov (United States)

    Wang, Rong; Xu, Yong; Liu, Bin

    2016-01-01

    Recombination is crucial for biological evolution, which provides many new combinations of genetic diversity. Accurate identification of recombination spots is useful for DNA function study. To improve the prediction accuracy, researchers have proposed several computational methods for recombination spot identification. The k-mer feature is one of the most useful features for modeling the properties and function of DNA sequences. However, it suffers from the inherent limitation. If the value of word length k is large, the occurrences of k-mers are closed to a binary variable, with a few k-mers present once and most k-mers are absent. This usually causes the sparse problem and reduces the classification accuracy. To solve this problem, we add gaps into k-mer and introduce a new feature called gapped k-mer (GKM) for identification of recombination spots. By using this feature, we present a new predictor called SVM-GKM, which combines the gapped k-mers and Support Vector Machine (SVM) for recombination spot identification. Experimental results on a widely used benchmark dataset show that SVM-GKM outperforms other highly related predictors. Therefore, SVM-GKM would be a powerful predictor for computational genomics. PMID:27030570

  10. On the evolutionary advantage of fitness-associated recombination.

    Science.gov (United States)

    Hadany, Lilach; Beker, Tuvik

    2003-12-01

    The adaptive value of recombination remains something of a puzzle. One of the basic problems is that recombination not only creates new and advantageous genetic combinations, but also breaks down existing good ones. A negative correlation between the fitness of an individual and its recombination rate would result in prolonged integrity of fitter genetic combinations while enabling less fit ones to produce new combinations. Such a correlation could be mediated by various factors, including stress responses, age, or direct DNA damage. For haploid population models, we show that an allele for such fitness-associated recombination (FAR) can spread both in asexual populations and in populations reproducing sexually at any uniform recombination rate. FAR also carries an advantage for the population as a whole, resulting in a higher average fitness at mutation-selection balance. These results are demonstrated in populations adapting to new environments as well as in well-adapted populations coping with deleterious mutations. Current experimental results providing evidence for the existence of FAR in nature are discussed. PMID:14704195

  11. Recombination-ready Sindbis replicon expression vectors for transgene expression

    Directory of Open Access Journals (Sweden)

    Olson Ken E

    2007-10-01

    Full Text Available Abstract Background Sindbis viruses have been widely used as tools to study gene function in cells. Despite the utility of these systems, the construction and production of alphavirus replicons is time consuming and inefficient due to potential additional restriction sites within the insert region and lack of directionality for insert ligation. In this report, we present a system useful for producing recombinant Sindbis replicons that uses lambda phage recombination technology to rapidly and specifically construct replicon expression plasmids that contain insert regions in the desired orientation. Results Recombination of the gene of interest with the replicon plasmid resulted in nearly 100% recombinants, each of which contained a correctly orientated insert. Replicons were easily produced in cell culture and packaged into pseudo-infectious viral particles. Insect and mammalian cells infected with pseudo-infectious viral particles expressed various transgenes at high levels. Finally, inserts from persistently replicating replicon RNA were easily isolated and recombined back into entry plasmids for sequencing and subsequent analysis. Conclusion Replication-ready replicon expression plasmids make the use of alphavirus replicons fast and easy as compared to traditional replicon production methods. This system represents a significant step forward in the utility and ease of use of alphavirus replicons in the study of gene function.

  12. CRISPR–Cas9-assisted recombineering in Lactobacillus reuteri

    Science.gov (United States)

    Oh, Jee-Hwan; van Pijkeren, Jan-Peter

    2014-01-01

    Clustered regularly interspaced palindromic repeats (CRISPRs) and the CRISPR-associated (Cas) nuclease protect bacteria and archeae from foreign DNA by site-specific cleavage of incoming DNA. Type-II CRISPR–Cas systems, such as the Streptococcus pyogenes CRISPR–Cas9 system, can be adapted such that Cas9 can be guided to a user-defined site in the chromosome to introduce double-stranded breaks. Here we have developed and optimized CRISPR–Cas9 function in the lactic acid bacterium Lactobacillus reuteri ATCC PTA 6475. We established proof-of-concept showing that CRISPR–Cas9 selection combined with single-stranded DNA (ssDNA) recombineering is a realistic approach to identify at high efficiencies edited cells in a lactic acid bacterium. We show for three independent targets that subtle changes in the bacterial genome can be recovered at efficiencies ranging from 90 to 100%. By combining CRISPR–Cas9 and recombineering, we successfully applied codon saturation mutagenesis in the L. reuteri chromosome. Also, CRISPR–Cas9 selection is critical to identify low-efficiency events such as oligonucleotide-mediated chromosome deletions. This also means that CRISPR–Cas9 selection will allow identification of recombinant cells in bacteria with low recombineering efficiencies, eliminating the need for ssDNA recombineering optimization procedures. We envision that CRISPR–Cas genome editing has the potential to change the landscape of genome editing in lactic acid bacteria, and other Gram-positive bacteria. PMID:25074379

  13. Novel Heterotypic Rox Sites for Combinatorial Dre Recombination Strategies

    Directory of Open Access Journals (Sweden)

    Katherine Chuang

    2016-03-01

    Full Text Available Site-specific recombinases (SSRs such as Cre are widely used in gene targeting and genetic approaches for cell labeling and manipulation. They mediate DNA strand exchange between two DNA molecules at dedicated recognition sites. Precise understanding of the Cre recombination mechanism, including the role of individual base pairs in its loxP target site, guided the generation of mutant lox sites that specifically recombine with themselves but not with the wild type loxP. This has led to the development of a variety of combinatorial Cre-dependent genetic strategies, such as multicolor reporters, irreversible inversions, or recombination-mediated cassette exchange. Dre, a Cre-related phage integrase that recognizes roxP sites, does not cross-react with the Cre-loxP system, but has similar recombination efficiency. We have previously described intersectional genetic strategies combining Dre and Cre. We now report a mutagenesis screen aimed at identifying roxP base pairs critical for self-recognition. We describe several rox variant sites that are incompatible with roxP, but are able to efficiently recombine with themselves in either purified systems or bacterial and eukaryotic tissue culture systems. These newly identified rox sites are not recognized by Cre, thus enabling potential combinatorial strategies involving Cre, Dre, and target loci including multiple loxP and roxP variants.

  14. Expression of recombination-activating genes and T cell receptor gene recombination in the human T cell leukemia cell line

    Institute of Scientific and Technical Information of China (English)

    ZOU Hong-yun; MA Li; MENG Min-jie; YAO Xin-sheng; LIN Ying; WU Zhen-qiang; HE Xiao-wei; WANG Ju-fang; WANG Xiao-ning

    2007-01-01

    Background Recent studies have suggested that mature T cells can change their specificity through reexpression of recombination-activating genes (RAG) and RAG-mediated V(D)J recombination. This process is named receptor revision and has been observed in mature peripheral T cells from transgenic mice and human donors. However, whether the receptor revision in mature T cells is a random or orientated process remains poorly understood. Here we used the Jurkat human T cell line, which represents a mature stage of T cell development, as a model to investigate the regulation of T cell receptor (TCR) gene recombination.Methods TCR Dβ-Jβ signal joint T cell receptor excision DNA circles (sjTRECs) were determined by nested and seminested PCR. Double-strand DNA breaks at recombination signal sequences (RSSs) in the TCRVβ chain locus were detected by ligation-mediated-PCR. Further analysis of the complementarity-determining region 3 (CDR3) size of the TCRVβ chain was examined by the TCR GeneScan technique.Results RAG1, RAG2, and three crucial components of the nonhomologous DNA end-joining (NHEJ) pathway were readily detected in Jurkat. Characteristics of junctional diversity of Dβ2-Jβ2 signal joints and ds RSS breaks associated with the Dβ25' and Dβ 23' sites were detected in DNA from Jurkat cells. CDR3 size and the gene sequences of the TCRVβ chain did not change during cell proliferation.Conclusions RAG1 and RAG2 and ongoing TCR gene recombination are coexpressed in Jurkat cells, but the ongoing recombination process may not play a role in modification of the TCR repertoire. However, the results suggest that Jurkat could be used as a model for studying the regulation of RAGs and V(D)J recombination and as a "special" model of the coexistence of TCR gene rearrangements and "negative" receptor revision.

  15. Production of biologically active recombinant human lactoferrin in Aspergillus oryzae.

    Science.gov (United States)

    Ward, P P; Lo, J Y; Duke, M; May, G S; Headon, D R; Conneely, O M

    1992-07-01

    We report the production of recombinant human lactoferrin in Aspergillus oryzae. Expression of human lactoferrin (hLF), a 78 kD glycoprotein, was achieved by placing the cDNA under the control of the A. oryzae alpha-amylase promoter and the 3' flanking region of the A. niger glucoamylase gene. Using this system, hLF is expressed and secreted into the growth medium at levels up to 25 mg/l. The recombinant lactoferrin is indistinguishable from human milk lactoferrin with respect to its size, immunoreactivity, and iron-binding capacity. The recombinant protein appears to be appropriately N-linked glycosylated and correctly processed at the N-terminus by the A. oryzae secretory apparatus. Lactoferrin is the largest heterologous protein and the first mammalian glycoprotein expressed in the Aspergillus system to date. Hence, this expression system appears suitable for the large-scale production and secretion of biologically active mammalian glycoproteins. PMID:1368268

  16. Radiative instabilities in plasmas: impurity motion and recombination effects

    International Nuclear Information System (INIS)

    Radiative instabilities in an impurity-seeded plasma are investigated when the plasma is supposed to be highly but partially ionized. Since in such plasmas radiative losses strongly depend on neutral and impurity densities, their dynamics are taken into account. As a result, a new radiative-recombination instability is found and described. We show that the influence of the ionization-recombination balance on plasma stability is sufficient for plasma densities above 1014 cm-3. The effects of a finite impurity Larmor radius are not small and play a stabilizing role as well as the thermal forces. On the other hand, compressibility of the magnetic field leads to plasma destabilization. We note that this radiative-recombination instability accumulates impurities in a cold zone while cleaning other regions. (Author)

  17. Taxing the Rich: Recombinations and Bubble Growth During Reionization

    CERN Document Server

    Furlanetto, S R; Furlanetto, Steven R.

    2005-01-01

    Reionization is inhomogeneous for two reasons: the clumpiness of the intergalactic medium (IGM) and clustering of the discrete ionizing sources. While numerical simulations can in principle take both into account, they are at present limited by small box sizes. On the other hand, analytic models have only examined the limiting cases of a clumpy IGM (with uniform ionizing emissivity) and clustered sources (embedded in a uniform IGM). Here, we present an analytic model for the evolving topology of reionization that includes both factors. At first, recombinations can be ignored and ionized bubbles grow primarily through major mergers. As a result, reionization resembles "punctuated equilibrium," with a series of well-separated sharp jumps in the ionizing background. These features are local effects and do not reflect similar jumps in the global ionized fraction. We then combine our bubble model with a simple description of recombinations in the IGM. We show that the bubbles stop growing when recombinations balan...

  18. Recombination methods in the dosimetry of mixed radiation

    International Nuclear Information System (INIS)

    The work describes the state of art of recombination methods developed for the dosimetry of mixed radiation fields. The existing theories of initial recombination of ions in gases is given. Recombination methods developed in IAE are reviewed in detail. The methods described here can be applied in mixed radiation fields of poorly known composition and practically unlimited energy range. Main dosimetric parameters such as absorbed dose, photon component to the absorbed dose, radiation quality factor, dose equivalent, ambient dose equivalent and some other quantities can be determined in single instrument. A novel method has been developed for determination of the energy loss distribution in the nanometric region. Experimental tests showed that the method is promising not only for radiation protection but also for radiobiological investigations. (author). 166 refs, 62 figs, 16 tabs

  19. Recombination Lines of CII in the Spectra of Planetary Nebulae

    CERN Document Server

    Sochi, Taha

    2010-01-01

    The current report presents the work carried out by the author to investigate the recombination lines of CII in the spectra of planetary nebulae. Two CIII targets were prepared and used to generate theoretical data required in the investigation of recombination lines that arise from collisions between electrons and ions in thin plasma found in planetary nebulae and other astrophysical objects. One of these targets contains 9 atomic terms while the other contains 26 terms. For each one of these targets, theoretical data concerning bound and autoionizing states were generated in the intermediate coupling approximation by R-matrix and Autostructure codes and compared to experimental data. The comparison revealed very good agreement. These theoretical data were then used to generate emissivity data and compare it to the carbon recombination lines found in the observational line list of Zhang et al [2005] on the planetary nebula NGC 7027. The main tool used in this analysis is the `Emissivity' code which is a prog...

  20. Recombination methods in the dosimetry of mixed radiation

    Energy Technology Data Exchange (ETDEWEB)

    Golnik, N. [Institute of Atomic Energy, Otwock-Swierk (Poland)

    1996-12-31

    The work describes the state of art of recombination methods developed for the dosimetry of mixed radiation fields. The existing theories of initial recombination of ions in gases is given. Recombination methods developed in IAE are reviewed in detail. The methods described here can be applied in mixed radiation fields of poorly known composition and practically unlimited energy range. Main dosimetric parameters such as absorbed dose, photon component to the absorbed dose, radiation quality factor, dose equivalent, ambient dose equivalent and some other quantities can be determined in single instrument. A novel method has been developed for determination of the energy loss distribution in the nanometric region. Experimental tests showed that the method is promising not only for radiation protection but also for radiobiological investigations. (author). 166 refs, 62 figs, 16 tabs.

  1. Radiative and interfacial recombination in CdTe heterostructures

    International Nuclear Information System (INIS)

    Double heterostructures (DH) were produced consisting of a CdTe film between two wide band gap barriers of CdMgTe alloy. A combined method was developed to quantify radiative and non-radiative recombination rates by examining the dependence of photoluminescence (PL) on both excitation intensity and time. The measured PL characteristics, and the interface state density extracted by modeling, indicate that the radiative efficiency of CdMgTe/CdTe DHs is comparable to that of AlGaAs/GaAs DHs, with interface state densities in the low 1010 cm−2 and carrier lifetimes as long as 240 ns. The radiative recombination coefficient of CdTe is found to be near 10−10 cm3s−1. CdTe film growth on bulk CdTe substrates resulted in a homoepitaxial interface layer with a high non-radiative recombination rate

  2. An Overview of the Molecular Mechanisms of Recombinational DNA Repair.

    Science.gov (United States)

    Kowalczykowski, Stephen C

    2015-11-01

    Recombinational DNA repair is a universal aspect of DNA metabolism and is essential for genomic integrity. It is a template-directed process that uses a second chromosomal copy (sister, daughter, or homolog) to ensure proper repair of broken chromosomes. The key steps of recombination are conserved from phage through human, and an overview of those steps is provided in this review. The first step is resection by helicases and nucleases to produce single-stranded DNA (ssDNA) that defines the homologous locus. The ssDNA is a scaffold for assembly of the RecA/RAD51 filament, which promotes the homology search. On finding homology, the nucleoprotein filament catalyzes exchange of DNA strands to form a joint molecule. Recombination is controlled by regulating the fate of both RecA/RAD51 filaments and DNA pairing intermediates. Finally, intermediates that mature into Holliday structures are disjoined by either nucleolytic resolution or topological dissolution. PMID:26525148

  3. Charge generation and recombination in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Meister, Michael; Wonneberger, Henrike; Li, Chen; Muellen, Klaus; Laquai, Frederic [Max-Planck-Institute for Polymer Research, Mainz (Germany)

    2010-07-01

    Charge recombination is one of the efficiency limiting processes in bulk heterojunction and dye-sensitized organic solar cells. To determine the presence of charges and the dynamics of charge generation and recombination photoinduced absorption spectroscopy (PIA) and transient absorption spectroscopy (TAS) are particularly useful techniques, since most of the investigated states are non-emissive. These methods allow to investigate all important mechanisms that lead to photocurrent generation beginning with the excitation of the dye, followed by charge transfer to a metal oxide semiconductor and regeneration of the dye by an electrolyte or an organic solid state hole conductor. In this study, we present spectroscopic experiments on dye-doped titanium dioxide films using novel all-organic perylene monoimide dyes as sensitizer with and without solid state hole conductor and on real device structures. We correlate the observed charge generation and recombination dynamics with the device efficiency to understand the relation between dye-structure, photophysics and device performance.

  4. Recombination and collisional X-UV lasers at ORSAY

    Energy Technology Data Exchange (ETDEWEB)

    Klisnick, A.; Carillon, A.; Dhez, P.; Goedtkindt, P.; Guennou, H.; Jamelot, G.; Jaegle, P.; Sureau, A.; Rus, B.; Zeitoun, P. (Laboratoire de Spectroscopie Atomique et Ionique, Universite Paris-Sud, Bat. 350, 91405 Orsay Cedex (France)); Chenais-Popovics, C.; Renaudin, P.; Rancu, O.; Gauthier, J.C. (LULI: CNRS National Facility, Laboratoire pour l' Utilisation des Lasers Intenses, Ecole Polytechnique, 91128 Palaiseau Cedex (France)); Back, C.A. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

    1995-01-10

    In this paper we describe the progress achieved recently in our laboratory in the field of X-ray lasers. Both collisional excitation and recombination pumped systems are under investigation. We show that the 5g-4f transition in lithium-like ions could bring out a significant increase of the gain-length accessible with recombination X-ray lasers. We present preliminary results on an absorption spectroscopy experiment designed to probe the ionization state of recombination X-ray laser plasmas. Finally we report on the observation of a strong amplified signal at 212 A, the wavelength of a 3p-3s (J=0--1) in neon-like zinc. [copyright] 1995 [ital American] [ital Institute] [ital of] [ital Physics

  5. Stability of small-scale baryon perturbations during cosmological recombination

    CERN Document Server

    Venumadhav, Tejaswi

    2014-01-01

    In this paper, we study small-scale fluctuations (baryon pressure sound waves) in the baryon fluid during recombination. In particular, we look at their evolution in the presence of relative velocities between baryons and photons on large scales ($k \\sim 10^{-1} \\ {\\rm Mpc}^{-1}$), which are naturally present during the era of decoupling. Previous work concluded that the fluctuations grow due to an instability of sound waves in a recombining plasma, but that the growth factor is small for typical cosmological models. These analyses model recombination in an inhomogenous universe as a perturbation to the parameters of the homogenous solution. We show that for relevant wavenumbers $k\\gtrsim 10^3\\ {\\rm Mpc}^{-1}$ the dynamics are significantly altered by the transport of both ionizing continuum ($h\

  6. [Study on recombinant BCG to prevent infections of intracellular pathogens].

    Science.gov (United States)

    Takeshi, Y

    2000-07-01

    Studies on recombinant BCG (rBCG) which my group carried out so far were reviewed. Recombinant BCG which secreted alpha antigen-fused foreign antigen was constructed and tested for its ability to induce protective immunity. Thus, rBCG secreting merozoite surface protein 1 (MSP1) of Plasmodium yoelii efficiently protected the infection more than recombinant MSP 1 mixed with artificial adjuvant RAS or IFA did. rBCG which secreted excess amounts of antigen 85 complex A inhibited the multiplication of M. leprae in the footpads of mice. rBCG which secreted alpha antigen-fused IL-2 stimulated peritoneal exudate cells of mice resulting in enhancing killing a bladder cancer cell line in vitro. PMID:10979272

  7. Attenuated vaccines can recombine to form virulent field viruses.

    Science.gov (United States)

    Lee, Sang-Won; Markham, Philip F; Coppo, Mauricio J C; Legione, Alistair R; Markham, John F; Noormohammadi, Amir H; Browning, Glenn F; Ficorilli, Nino; Hartley, Carol A; Devlin, Joanne M

    2012-07-13

    Recombination between herpesviruses has been seen in vitro and in vivo under experimental conditions. This has raised safety concerns about using attenuated herpesvirus vaccines in human and veterinary medicine and adds to other known concerns associated with their use, including reversion to virulence and disease arising from recurrent reactivation of lifelong chronic infection. We used high-throughput sequencing to investigate relationships between emergent field strains and vaccine strains of infectious laryngotracheitis virus (ILTV, gallid herpesvirus 1). We show that independent recombination events between distinct attenuated vaccine strains resulted in virulent recombinant viruses that became the dominant strains responsible for widespread disease in Australian commercial poultry flocks. These findings highlight the risks of using multiple different attenuated herpesvirus vaccines, or vectors, in the same populations. PMID:22798607

  8. Thermalisation and recombination of subexcitation electrons in solid water

    Energy Technology Data Exchange (ETDEWEB)

    Goulet, T.; Jay-Gerin, J.-P. (Sherbrooke Univ., PQ (Canada). Faculte de Medicine); Patau, J.-P. (Toulouse-3 Univ., 31 (France))

    1990-01-01

    The results of Monte Carlo simulations of the thermalisation of subexcitation electrons in solid water are reported. In the simulations, the possibility is taken into account that, prior to being thermalised, the electrons either recombine with their parent cation (H{sub 2}O{sup +}), or undergo a dissociative attachment to water molecules. A particular emphasis is placed on the description of the recombination process and on the influence of the parent cation on the electron's motion. The simulations are performed for different initial electron energies E{sub o} in the subexcitations energy range (i.e. E{sub o} < 7.4 eV). For each of these energies, the mean thermalisation distance {sub th} and time {sub th} are determined, as well as the proportions P{sub rec} and P{sub dis} of subexcitation electrons which, instead of thermalising, undergo recombination or dissociative attachment. (author).

  9. Matter-wave recombiners for trapped Bose-Einstein condensates

    Science.gov (United States)

    Berrada, T.; van Frank, S.; Bücker, R.; Schumm, T.; Schaff, J.-F.; Schmiedmayer, J.; Julía-Díaz, B.; Polls, A.

    2016-06-01

    Interferometry with trapped atomic Bose-Einstein condensates (BECs) requires the development of techniques to recombine the two paths of the interferometer and map the accumulated phase difference to a measurable atom number difference. We have implemented and compared two recombining procedures in a double-well-based BEC interferometer. The first procedure utilizes the bosonic Josephson effect and controlled tunneling of atoms through the potential barrier, similar to laser light in an optical fiber coupler. The second one relies on the interference of the reflected and transmitted parts of the BEC wave function when impinging on the potential barrier, analogous to light impinging on a half-silvered mirror. Both schemes were implemented successfully, yielding an interferometric contrast of ˜20 % and 42% respectively. Building efficient matter-wave recombiners represents an important step towards the coherent manipulation of external quantum superposition states of BECs.

  10. Master Equation for Hydrogen Recombination on Grain Surfaces

    CERN Document Server

    Biham, O; Pirronello, V; Vidali, G; Biham, Ofer; Furman, Itay; Pirronello, Valerio; Vidali, Gianfranco

    2000-01-01

    Recent experimental results on the formation of molecular hydrogen on astrophysically relevant surfaces under conditions similar to those encountered in the interstellar medium provided useful quantitative information about these processes. Rate equation analysis of experiments on olivine and amorphous carbon surfaces provided the activation energy barriers for the diffusion and desorption processes relevant to hydrogen recombination on these surfaces. However, the suitability of rate equations for the simulation of hydrogen recombination on interstellar grains, where there might be very few atoms on a grain at any given time, has been questioned. To resolve this problem, we introduce a master equation that takes into account both the discrete nature of the H atoms and the fluctuations in the number of atoms on a grain. The hydrogen recombination rate on microscopic grains, as a function of grain size and temperature, is then calculated using the master equation. The results are compared to those obtained fro...

  11. Recombinant production of mecasermin in E. coli expression system.

    Science.gov (United States)

    Jafari, S; Babaeipour, V; Seyedi, H A Eslampanah; Rahaie, M; Mofid, M R; Haddad, L; Namvaran, M M; Fallah, J

    2014-01-01

    Human Insulin-like growth factor 1 (hIGF-1) consists of 70 amino acids in a single chain with three intermolecular disulfide bridges possessing valuable therapeutic effects. To date, numerous variants of specifically engineered hIGF-1 have been produced so as to improve hIGF-1 biological activity, stability and stronger binding to IGF-1 receptor. Mecasermin is one of the modified variants with one amino acid substitution near the N-terminal (T4I) approved for the treatment of growth failure diabetes, wound healing, amyotrophic lateral sclerosis and severe primary IGF-1 deficiency. No scientific report for recombinant production of mecasermin in Escherichia coli (E. coli) expression system has been sofar reported. In the present study, we therefore investigated the overexpression of mecasermin in two different E. coli strains in order to obtain higher yield of recombinant protein. To achieve this goal, mecasermin DNA encoding sequence was designed based on polypeptide sequence, optimized according to E. coli codon preference, and cloned in pET15b. Recombinant vector, pET15-mecasermin, transferred into two E. coli strains rigami B (DE3) and BL21 (DE3) and induced for expression in a small scale. Results revealed the E. coli Origami B (DE3) expression system was a preferable host for mecasermin production due to its high expression level being around twice as much as BL21 (DE3). Large scale mecasermin production was performed in batch culture and produced recombinant protein specifically confirmed by western blotting and mass spectroscopy. Since major part of recombinant mecasermin was expressed as inclusion body, isolation and refolding was accomplished through developed purification procedure, and finally recombinant protein was successfully purified by gel filtration chromatography. PMID:26339260

  12. Short telomeres initiate telomere recombination in primary and tumor cells.

    Directory of Open Access Journals (Sweden)

    Tammy A Morrish

    2009-01-01

    Full Text Available Human tumors that lack telomerase maintain telomeres by alternative lengthening mechanisms. Tumors can also form in telomerase-deficient mice; however, the genetic mechanism responsible for tumor growth without telomerase is unknown. In yeast, several different recombination pathways maintain telomeres in the absence of telomerase-some result in telomere maintenance with minimal effects on telomere length. To examine non-telomerase mechanisms for telomere maintenance in mammalian cells, we used primary cells and lymphomas from telomerase-deficient mice (mTR-/- and Emumyc+mTR-/- and CAST/EiJ mouse embryonic fibroblast cells. These cells were analyzed using pq-ratio analysis, telomere length distribution outliers, CO-FISH, Q-FISH, and multicolor FISH to detect subtelomeric recombination. Telomere length was maintained during long-term growth in vivo and in vitro. Long telomeres, characteristic of human ALT cells, were not observed in either late passage or mTR-/- tumor cells; instead, we observed only minimal changes in telomere length. Telomere length variation and subtelomeric recombination were frequent in cells with short telomeres, indicating that length maintenance is due to telomeric recombination. We also detected telomere length changes in primary mTR-/- cells that had short telomeres. Using mouse mTR+/- and human hTERT+/- primary cells with short telomeres, we found frequent length changes indicative of recombination. We conclude that telomere maintenance by non-telomerase mechanisms, including recombination, occurs in primary cells and is initiated by short telomeres, even in the presence of telomerase. Most intriguing, our data indicate that some non-telomerase telomere maintenance mechanisms occur without a significant increase in telomere length.

  13. Oligonucleotide recombination in corynebacteria without the expression of exogenous recombinases.

    Science.gov (United States)

    Krylov, Alexander A; Kolontaevsky, Egor E; Mashko, Sergey V

    2014-10-01

    Brevibacterium lactofermentum and Corynebacterium glutamicum are important biotechnology species of the genus Corynebacterium. The single-strand DNA annealing protein (SSAP)-independent oligonucleotide-mediated recombination procedure was successfully applied to the commonly used wild-type strains B. lactofermentum AJ1511 and C. glutamicum ATCC13032. When the rpsL gene was used as a target, the optimized protocol yielded up to (1.4±0.3)×10(3) and (6.7±1.3)×10(3) streptomycin-resistant colonies per 10(8) viable cells for the corresponding strains. We tested the influence of several parameters that are known to enhance the efficiency of oligonucleotide-mediated recombination in other bacterial species. Among them, increasing the concentration of oligonucleotides and targeting the lagging strand of the chromosome have proven to have positive effects on both of the tested species. No difference in the efficiency of recombination was observed between the oligonucleotides phosphorothiorated at the 5' ends and the unmodified oligonucleotides or between the oligonucleotides with four mutated nucleotides and those with one mutated nucleotide. The described approach demonstrates that during the adaptation of the recombineering technique, testing SSAP-independent oligonucleotide-mediated recombination could be a good starting point. Such testing could decrease the probability of an incorrect interpretation of the effect of exogenous protein factors (such as SSAP and/or corresponding exonucleases) due to non-optimal experimental conditions. In addition, SSAP-independent recombination itself could be useful in combination with suitable selection/enrichment methods. PMID:25087479

  14. Electron solvation and geminate ion recombination in ionic liquids

    International Nuclear Information System (INIS)

    The behavior of radiation-induced active species in ionic liquids attract much attention from view point of radiation induced decomposition and reaction in ionic liquids. The formation process, lifetime, yield and reactivity of solvated electrons were studied in alkyl ammonium ionic liquid by electron beam pulse radiolysis method. As a result, the G-value of the solvated electron is about 1, the lifetime is about 300 ns, the high efficiency reaction between the dry electron and solute were clarified. Most of the ionized electron would recombine with parent radical cation geminately. Pre-solvated electron reaction and geminate ion recombination were investigated using the femtosecond pulse radiolysis system. (author)

  15. The current state of recombinant allergens for immunotherapy

    DEFF Research Database (Denmark)

    Pauli, Gabrielle; Malling, H-J

    2010-01-01

    Subcutaneous immunotherapy is a well documented treatment of allergic rhinitis and asthma. The majority of the disadvantages of the treatment are related to the poor quality of the natural allergen extracts which can contain varying amounts of individual allergens including allergens to which the...... patient may not be sensitized. Recombinant allergens offer a possibility to use well defined molecules with consistent pharmaceutical quality defined in mass units. The proof of concept of the clinical efficacy of recombinant allergens is based on two studies published as full articles....

  16. Recombination patterns reveal information about centromere location on linkage maps

    DEFF Research Database (Denmark)

    Limborg, Morten T.; McKinney, Garrett J.; Seeb, Lisa W.;

    2016-01-01

    , approximate centromere placement is possible by phasing the same data used to generate linkage maps. Assuming one obligate crossover per chromosome arm, information about centromere location can be revealed by tracking the accumulated recombination frequency along linkage groups, similar to half....... mykiss) characterized by low and unevenly distributed recombination – a general feature of male meiosis in many species. Further, a high frequency of double crossovers along chromosome arms in barley reduced resolution for locating centromeric regions on most linkage groups. Despite these limitations...

  17. Radiative recombination and photon recycling in gallium arsenide solar cells

    Science.gov (United States)

    Lundstrom, M. S.; Melloch, M. R.; Lush, G. B.; Patkar, M. P.; Young, M.; Durbin, S. M.; Gray, J. L.; MacMillan, H. F.; Keyes, B. M.; Levi, D. H.; Ahrenkiel, R. K.

    1992-12-01

    This talk reviews experimental work to develop a detailed understanding of radiative recombination in n-GaAs. Photoluminescence decay studies of minority carrier lifetimes versus doping in n-GaAs are presented. We show that when the substrate is removed by etching, photon recycling is enhanced, and lifetimes increase by nearly a factor of 10. The doping-dependent absorption coefficient is measured, and detailed balance arguments are used to relate absorption and recombination. Modeling surfaces, verified by comparison with experiments, are used to examine the effects of recycling in conventional solar cells and to explore new design options.

  18. Photon Angular Distribution and Polarization of Radiative Recombination

    Institute of Scientific and Technical Information of China (English)

    OU Wei-Ying; SHEN Tian-Ming; CHEN Chong-Yang; Roger Hutton; ZOU Ya-Ming

    2005-01-01

    @@ A systematic study is carried out on the angular distribution and polarization of photons emitted following radiative-recombination of bare and He-like ions of Ne, Ar, Ni and Mo with a unidirectional electron beam. In order to incorporate the screening effect due to inner-shell electrons, a distorted wave method is used. Scaling rules for polarization of the photon following radiative recombination to both bare and He-like ions are given for the incident energy regions up to six times the ionization threshold energy of the final state.

  19. Ig heavy chain class switch recombination: mechanism and regulation

    OpenAIRE

    Stavnezer, Janet; Schrader, Carol E.

    2014-01-01

    Ig heavy chain class switching occurs rapidly after activation of mature naïve B cells, resulting in a switch from expressing IgM and IgD to expression of IgG, IgE, or IgA; this switch improves the ability of antibodies to remove the pathogen that induces the humoral immune response. Class switching occurs by a deletional recombination between two different switch (S) regions, each of which is associated with a heavy chain constant (CH) region gene. Class switch recombination (CSR) is instiga...

  20. Influence of magnetic fields on recombination rates of Au25+

    International Nuclear Information System (INIS)

    Recombination of Au25+-ions has been investigated in a single-pass merged-beams experiment at the UNILAC of GSI in Darmstadt. Very low energies in the electron-ion center-of-mass frame were particularly addressed. At Erel = 0 eV we found a recombination rate exceeding the expectations by a factor of 365. For further investigation of this enhancement, the electron density and the magnetic field guiding the electron beam were varied. While an increase of the electron density by a factor of 10 had little influence, the measured rate coefficient increased significantly with the magnetic field strength. (orig.)

  1. A recombinant single chain antibody interleukin-2 fusion protein.

    OpenAIRE

    Savage, P; So, A; Spooner, R A; Epenetos, A. A.

    1993-01-01

    Recombinant interleukin-2 (rIL-2) therapy has been shown to be of value in the treatment of some cases of melanoma and renal cell carcinoma. However its use can be limited by severe systemic toxicity. Targeting rIL-2 to the tumour should improve the anti-tumour immune response and decrease the systemic toxicity. With this aim we have employed recombinant DNA techniques to construct a single chain antibody interleukin-2 fusion protein (SCA-IL-2). The protein used in this model system comprises...

  2. Recombination between satellite RNAs of turnip crinkle virus.

    OpenAIRE

    Cascone, P J; Carpenter, C. D.; Li, X.H.; Simon, A. E.

    1990-01-01

    Turnip crinkle virus (TCV) is associated with satellite (sat) RNAs (sat-RNA D, sat-RNA F), defective interfering (DI) RNAs (DI RNA G, DI1 RNA), and one RNA with properties of both sat-RNAs and DI RNAs (sat-RNA C). When plants were inoculated with TCV, sat-RNA D and in vitro sat-RNA C transcripts containing non-viable mutations in the 5' domain, recombinant sat-RNAs were recovered. These recombinants were composed of sat-RNA D at the 5' end and sat-RNA C sequences at the 3' end. Analysis of 20...

  3. Influence of manganese ions on recombination luminescence in potassium phospate

    International Nuclear Information System (INIS)

    The investigation of recombination luminescence was carried out for crystal KDP doped by manganese ions after full and partial dehydration. It was established that manganese ions bring about increase the velocities of radiation defects accumulation in matrix. It was expected the appearance of two new TL peaks are connected with influence radiation defects thermal stability in matrix by impurity ions. The TL peal 100 K is connected with defect PO32-. The manganese ions become ion replacement after full dehydration. The radiation induced impurity defects are a centers of recombination. (author)

  4. Hydrogen Recombination Rates of Plate-type Passive Auto-catalytic Recombiner

    International Nuclear Information System (INIS)

    The hydrogen mitigation system may include igniters, passive autocatalytic recombiner (PAR), and venting or dilution system. Recently PAR is commonly used as a main component of HMS in a NPP containment because of its passive nature. PARs are categorized by the shape and material of catalytic surface. Catalytic surface coated by platinum is mostly used for the hydrogen recombiners. The shapes of the catalytic surface can be grouped into plate type, honeycomb type and porous media type. Among them, the plate-type PAR is well tested by many experiments. PAR performance analysis can be approached by a multi-scale method which is composed of micro, meso and macro scales. The criterion of the scaling is the ratio of thickness of boundary layer developed on a catalytic surface to representative length of a computational domain. Mass diffusion in the boundary layer must be resolved in the micro scale analysis. In a lumped parameter (LP) analysis using a system code such as MAAP or MELCOR, the chamber of the PAR is much smaller than a computational node. The hydrogen depletion by a PAR is modeled as a source of mass and energy conservation equations. Te catalytic surface reaction of hydrogen must be modeled by a volume-averaged correlation. In this study, a micro scale analysis method is developed using libraries in OpenFOAM to evaluate a hydrogen depletion rate depending on parameters such as size and number of plates and plate arrangement. The analysis code is validated by simulating REKO-3 experiment. And hydrogen depletion analysis is conducted by changing the plate arrangement as a trial of the performance enhancement of a PAR. In this study, a numerical code for an analysis of a PAR performance in a micro scale has been developed by using OpenFOAM libraries. The physical and numerical models were validated by simulating the REKO-3 experiment. As a try to enhance the performance of the plate-type PAR, it was proposed to apply a staggered two-layer arrangement of the

  5. Hydrogen Recombination Rates of Plate-type Passive Auto-catalytic Recombiner

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jongtae; Hong, Seong-Wan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Gun Hong [Kyungwon E-C Co., Seongnam (Korea, Republic of)

    2014-10-15

    The hydrogen mitigation system may include igniters, passive autocatalytic recombiner (PAR), and venting or dilution system. Recently PAR is commonly used as a main component of HMS in a NPP containment because of its passive nature. PARs are categorized by the shape and material of catalytic surface. Catalytic surface coated by platinum is mostly used for the hydrogen recombiners. The shapes of the catalytic surface can be grouped into plate type, honeycomb type and porous media type. Among them, the plate-type PAR is well tested by many experiments. PAR performance analysis can be approached by a multi-scale method which is composed of micro, meso and macro scales. The criterion of the scaling is the ratio of thickness of boundary layer developed on a catalytic surface to representative length of a computational domain. Mass diffusion in the boundary layer must be resolved in the micro scale analysis. In a lumped parameter (LP) analysis using a system code such as MAAP or MELCOR, the chamber of the PAR is much smaller than a computational node. The hydrogen depletion by a PAR is modeled as a source of mass and energy conservation equations. Te catalytic surface reaction of hydrogen must be modeled by a volume-averaged correlation. In this study, a micro scale analysis method is developed using libraries in OpenFOAM to evaluate a hydrogen depletion rate depending on parameters such as size and number of plates and plate arrangement. The analysis code is validated by simulating REKO-3 experiment. And hydrogen depletion analysis is conducted by changing the plate arrangement as a trial of the performance enhancement of a PAR. In this study, a numerical code for an analysis of a PAR performance in a micro scale has been developed by using OpenFOAM libraries. The physical and numerical models were validated by simulating the REKO-3 experiment. As a try to enhance the performance of the plate-type PAR, it was proposed to apply a staggered two-layer arrangement of the

  6. Productive homologous and non-homologous recombination of hepatitis C virus in cell culture.

    Directory of Open Access Journals (Sweden)

    Troels K H Scheel

    2013-03-01

    Full Text Available Genetic recombination is an important mechanism for increasing diversity of RNA viruses, and constitutes a viral escape mechanism to host immune responses and to treatment with antiviral compounds. Although rare, epidemiologically important hepatitis C virus (HCV recombinants have been reported. In addition, recombination is an important regulatory mechanism of cytopathogenicity for the related pestiviruses. Here we describe recombination of HCV RNA in cell culture leading to production of infectious virus. Initially, hepatoma cells were co-transfected with a replicating JFH1ΔE1E2 genome (genotype 2a lacking functional envelope genes and strain J6 (2a, which has functional envelope genes but does not replicate in culture. After an initial decrease in the number of HCV positive cells, infection spread after 13-36 days. Sequencing of recovered viruses revealed non-homologous recombinants with J6 sequence from the 5' end to the NS2-NS3 region followed by JFH1 sequence from Core to the 3' end. These recombinants carried duplicated sequence of up to 2400 nucleotides. HCV replication was not required for recombination, as recombinants were observed in most experiments even when two replication incompetent genomes were co-transfected. Reverse genetic studies verified the viability of representative recombinants. After serial passage, subsequent recombination events reducing or eliminating the duplicated region were observed for some but not all recombinants. Furthermore, we found that inter-genotypic recombination could occur, but at a lower frequency than intra-genotypic recombination. Productive recombination of attenuated HCV genomes depended on expression of all HCV proteins and tolerated duplicated sequence. In general, no strong site specificity was observed. Non-homologous recombination was observed in most cases, while few homologous events were identified. A better understanding of HCV recombination could help identification of natural

  7. Role of bacterial and phage recombination systems and of DNA replication in genetic recombination of UV-irradiated phage lambda

    International Nuclear Information System (INIS)

    A study was made in E. coli K12 of the influence of the bacterial Rec and phage lambda Red recombination systems on the rescue of the 0+ gene from the prophage by a superinfecting 0- phage, UV irradiated or not. In the absence of UV irradiation the Red system produces more recombinants than does the Rec system, and its action requires DNA replication. The presence of UV lesions in the lambda DNA facilitates the action of the Rec system, which is more efficient in this instance than the Red system and can act in the absence of DNA replication. In all cases, there is a cooperation between the two generalized recombination systems. (orig.)

  8. Sum rules for meson and baryon production in the quark recombination model

    International Nuclear Information System (INIS)

    A quark-recombination model with quark distributions according to a generalized Kuti-Weisskopf model is used. Mesons are formed by v-s (valence-sea) and s-s recombination, baryons by vvv, vvs, vss and sss recombination. Sum rules for energy momentum conservation, baryon number, valence and sea quarks are shown to constrain the recombination parameters of the model significantly. The resulting model is consistent with experimental data. While the sss recombination into baryons is found to be quite normal we find a strong enhancement of ss recombination into mesons. This enhanced ss term represents in the model the central meson production via gluons. (author)

  9. High-Resolution Mapping of Homologous Recombination Events in rad3 Hyper-Recombination Mutants in Yeast.

    Directory of Open Access Journals (Sweden)

    Sabrina L Andersen

    2016-03-01

    Full Text Available The Saccharomyces cerevisae RAD3 gene is the homolog of human XPD, an essential gene encoding a DNA helicase of the TFIIH complex involved in both nucleotide excision repair (NER and transcription. Some mutant alleles of RAD3 (rad3-101 and rad3-102 have partial defects in DNA repair and a strong hyper-recombination (hyper-Rec phenotype. Previous studies showed that the hyper-Rec phenotype associated with rad3-101 and rad3-102 can be explained as a consequence of persistent single-stranded DNA gaps that are converted to recombinogenic double-strand breaks (DSBs by replication. The systems previously used to characterize the hyper-Rec phenotype of rad3 strains do not detect the reciprocal products of mitotic recombination. We have further characterized these events using a system in which the reciprocal products of mitotic recombination are recovered. Both rad3-101 and rad3-102 elevate the frequency of reciprocal crossovers about 100-fold. Mapping of these events shows that three-quarters of these crossovers reflect DSBs formed at the same positions in both sister chromatids (double sister-chromatid breaks, DSCBs. The remainder reflects DSBs formed in single chromatids (single chromatid breaks, SCBs. The ratio of DSCBs to SCBs is similar to that observed for spontaneous recombination events in wild-type cells. We mapped 216 unselected genomic alterations throughout the genome including crossovers, gene conversions, deletions, and duplications. We found a significant association between the location of these recombination events and regions with elevated gamma-H2AX. In addition, there was a hotspot for deletions and duplications at the IMA2 and HXT11 genes near the left end of chromosome XV. A comparison of these data with our previous analysis of spontaneous mitotic recombination events suggests that a sub-set of spontaneous events in wild-type cells may be initiated by incomplete NER reactions, and that DSCBs, which cannot be repaired by sister

  10. Same Period Emission and Recombination in Non-Sequential Double Recombination High-Harmonic Generation in H$_2$

    CERN Document Server

    Hansen, Kenneth K

    2016-01-01

    Non-sequential double recombination (NSDR) high-order harmonic generation (HHG) is studied in a molecular system. We observe a unique molecular two-electron effect with a characteristic cutoff in the HHG spectrum at higher energies than what was previously seen for NSDR HHG in atoms. The effect is corroborated with a classical model where it is found that the effect is sensitive to the molecular potential and originates from same period emission and recombination (SPEaR) of two electrons. The effect persists for intermediate nuclear distances of $R \\gtrsim 8.0$ a.u.

  11. Tailoring Charge Recombination in Photoelectrodes Using Oxide Nanostructures

    DEFF Research Database (Denmark)

    Iandolo, Beniamino; Wickman, Björn; Svensson, Elin;

    2016-01-01

    . The control mechanism relies on the formation of dipole-like electric fields at the interface that, depending on the field direction, attract or repel minority carriers from underneath the disks. The charge recombination rate can be controlled through the choice of oxide material and the surface coverage...

  12. Monochromatic thermoluminescence and models of recombination kinetics in ionic solids

    OpenAIRE

    Ratnam, V.; Gartia, R.; Acharya, B.

    1980-01-01

    Thermoluminescence (TL) emission spectra, monochromatic isothermal decay and photostimulated monochromatic TL results are utilized to establish the recombination kinetics as well as the nature of charge carriers in the TL of KCl : Mn system. These results support our earlier model wherein diinterstitials are shown to play the intermediate role in the TL process.

  13. Experimental investigation of ion-ion recombination at atmospheric conditions

    OpenAIRE

    A. Franchin; S. Ehrhart; Leppä, J.; Nieminen, T.; Gagné, S.; Schobesberger, S.; D. Wimmer; J. Duplissy; Riccobono, F.; Dunne, E; L. Rondo; Downard, A.; BIANCHI, F.; Kupc, A.; Tsagkogeorgas, G.

    2015-01-01

    We present the results of laboratory measurements of the ion-ion recombination coefficient at different temperatures, relative humidities and concentrations of ozone and sulfur dioxide. The experiments were carried out using the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at CERN, the walls of which are made of conductive material, making it possible to measure s...

  14. Treatment of anemia of nephrotic syndrome with recombinant erythropoietin

    NARCIS (Netherlands)

    Gansevoort, RT; Vaziri, ND; deJong, PE

    1996-01-01

    Nephrotic syndrome has been recently shown to cause erythropoietin (EPO) deficiency in humans and experimental models. However, efficacy and safety of recombinant EPO (rEPO) in the treatment of the associated anemia has not been previously investigated. We report a patient with nephrotic syndrome an

  15. Haemostatic aspects of recombinant human erythropoietin in colorectal surgery

    DEFF Research Database (Denmark)

    Poulsen, K A; Qvist, N; Winther, K;

    1998-01-01

    OBJECTIVE: To find out whether recombinant human erythropoietin (r-HuEPO) given perioperatively has any effect on haemostatic activity in patients undergoing elective colorectal resection. DESIGN: A placebo-controlled double-blind study. SETTING: Odense university hospital, Denmark. SUBJECTS: 24...

  16. The electron-ionized donor recombination in semiconductors

    International Nuclear Information System (INIS)

    A calculation is presented of the recombination cross section of a conduction electron and a donor impurity. Donor states are described in a many-valley model. It is shown that, for Si, the main contribution comes from the intravalley terms and that the intervalley terms are completely negligible. (author)

  17. Recombinant pharmaceuticals from microbial cells: a 2015 update.

    Science.gov (United States)

    Sanchez-Garcia, Laura; Martín, Lucas; Mangues, Ramon; Ferrer-Miralles, Neus; Vázquez, Esther; Villaverde, Antonio

    2016-01-01

    Diabetes, growth or clotting disorders are among the spectrum of human diseases related to protein absence or malfunction. Since these pathologies cannot be yet regularly treated by gene therapy, the administration of functional proteins produced ex vivo is required. As both protein extraction from natural producers and chemical synthesis undergo inherent constraints that limit regular large-scale production, recombinant DNA technologies have rapidly become a choice for therapeutic protein production. The spectrum of organisms exploited as recombinant cell factories has expanded from the early predominating Escherichia coli to alternative bacteria, yeasts, insect cells and especially mammalian cells, which benefit from metabolic and protein processing pathways similar to those in human cells. Up to date, around 650 protein drugs have been worldwide approved, among which about 400 are obtained by recombinant technologies. Other 1300 recombinant pharmaceuticals are under development, with a clear tendency towards engineered versions with improved performance and new functionalities regarding the conventional, plain protein species. This trend is exemplified by the examination of the contemporary protein-based drugs developed for cancer treatment. PMID:26861699

  18. Recombinant genomes which express chloramphenicol acetyltransferase in mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Gorman, C.M.; Moffat, L.F.; Howard, B.H.

    1982-09-01

    The authors constructed a series of recombinant genomes which directed expression of the enzyme chloramphenicol acetyltransferase (CAT) in mammalian cells. The prototype recombinant in this series, pSV2-cat, consisted of the beta-lactamase gene and origin of replication from pBR322 coupled to a simian virus 40 (SV40) early transcription region into which CAT coding sequences were inserted. Readily measured levels of CAT accumulated within 48 h after the introduction of pSV2-cat DNA into African green monkey kidney CV-1 cells. Because endogenous CAT activity is not present in CV-1 or other mammalian cells, and because rapid, sensitive assays for CAT activity are available, these recombinants provided a uniquely convenient system for monitoring the expression of foreign DNAs in tissue culture cells. To demonstrate the usefulness of this system, we constructed derivatives of pSV2-cat from which part or all of the SV 40 promoter region was removed. Deletion of one copy of the 72-base-pair repeat sequence in the SV40 promoter caused no significant decrease in CAT synthesis in monkey kidney CV-1 cells; however, an additional deletion of 50 base pairs from the second copy of the repeats reduced CAT synthesis to 11% of its level in the wild type. They also constructed a recombinant, pSVO-cat, in which the entire SV40 promoter region was removed and a unique HindIII site was substituted for the insertion of other promoter sequences.

  19. Identification of Recombination and Positively Selected Genes in Brucella.

    Science.gov (United States)

    Vishnu, Udayakumar S; Sankarasubramanian, Jagadesan; Sridhar, Jayavel; Gunasekaran, Paramasamy; Rajendhran, Jeyaprakash

    2015-12-01

    Brucella is a facultative intracellular bacterium belongs to the class alpha proteobacteria. It causes zoonotic disease brucellosis to wide range of animals. Brucella species are highly conserved in nucleotide level. Here, we employed a comparative genomics approach to examine the role of homologous recombination and positive selection in the evolution of Brucella. For the analysis, we have selected 19 complete genomes from 8 species of Brucella. Among the 1599 core genome predicted, 24 genes were showing signals of recombination but no significant breakpoint was found. The analysis revealed that recombination events are less frequent and the impact of recombination occurred is negligible on the evolution of Brucella. This leads to the view that Brucella is clonally evolved. On other hand, 56 genes (3.5 % of core genome) were showing signals of positive selection. Results suggest that natural selection plays an important role in the evolution of Brucella. Some of the genes that are responsible for the pathogenesis of Brucella were found positively selected, presumably due to their role in avoidance of the host immune system. PMID:26543263

  20. Thermostimulated recombination processes in LiBaF3 crystals

    International Nuclear Information System (INIS)

    Full text: Creation of radiation defects in LiBaF3 crystals at 10 K and their thermostimulated recombination process are investigated. Methods of optical absorption, thermal bleaching of colour centres, thermostimulated luminescence (TSL) and fractional glow technique are used. The radiation defects annealed in multi stage process accompanied with thermo-luminescence at 20, 46, 105, 130, 170, 210 and 270 K. Possible parameters of recombination partners are determinate by the difference of optical absorption spectra measured before and after TSL peaks. Taking into account the known absorption bands of F-centres and 'sign' of recombination process we consider: - The TSL peak at 20 K arises due to the delocalisation of H-centres. The absorption band at 3.8 eV with half-width 1.1 eV can be attributed to the Hcentre. - The TSL peaks at 105 K and 130 K in LiBaF3 are governed by thermoactivated migration-tunnelling recombination of self-trapped holes. Presence of two TSL peaks of Vk-centres at 105 and 130 K indicates that the 60 deg and the 90 deg migration hops occur. The expected absorption bands of Vk-centres are at 3.2 and 4.3 eV

  1. Isolation of recombinant cysteine dioxygenase protein from Trichophyton mentagrophytes

    Czech Academy of Sciences Publication Activity Database

    Kašperová, A.; Kunert, J.; Horynová, M.; Weigl, E.; Sebela, M.; Lenobel, René; Raška, M.

    2011-01-01

    Roč. 54, č. 5 (2011), E456-E462. ISSN 0933-7407 R&D Projects: GA ČR GA301/08/1649 Institutional research plan: CEZ:AV0Z50380511 Keywords : Cysteine dioxygenase * dermatophytes * recombinant protein * keratinolytic fungi * cDNA Subject RIV: CE - Biochemistry Impact factor: 2.247, year: 2011

  2. Isomerization of metastable amine radical cations by dissociation-recombination

    DEFF Research Database (Denmark)

    Pedersen, Anders Holmen; Nielsen, Christian Benedikt; Bojesen, Gustav;

    2015-01-01

    The metastable molecular ions of primary aliphatic amines branched at C2 can isomerize by cleavage-recombination, thereby facilitating fragmentation reactions that require less energy than simple cleavage of the initial molecular ion. This process complements the reactions described by Audier to...

  3. Doping in the recombinant era: strategies and counterstrategies.

    Science.gov (United States)

    Azzazy, Hassan M E; Mansour, Mai M H; Christenson, Robert H

    2005-11-01

    Advances in recombinant DNA technology have created one of the most powerful weapons in the current doping arsenal: recombinant proteins [Sweeney HL. Gene doping. Sci Am 2004;291:62-9; Unal M, Ozer Unal D. Gene doping in sports. Sports Med 2004;34:357-62]. Recombinant erythropoietin (EPO) and human growth hormone (hGH) are currently being abused but are fortunately detectable either directly by employing isoelectric focusing and immunoassays or indirectly by assessing changes in selected hematopoietic parameters. The detection is technically demanding due to the extent of similarity between the recombinant proteins and their endogenous counterparts. Another issue facing detection efforts is the speed and conditions at which blood samples are collected and analyzed in a sports setting. Recently, gene doping, which stemmed out of legitimate gene therapy trials, has emerged as the next level of doping. Erythropoietin (EPO), human growth hormone (hGH), insulin-like growth factor-1 (IGF-1), peroxisome proliferator-activated receptor-delta (PPAR delta), and myostatin inhibitor genes have been identified as primary targets for doping. Sports clinical scientists today are racing against the clock because assuring the continued integrity of sports competition depends on their ability to outpace the efforts of dopers by developing new detection strategies. PMID:16286094

  4. A Collaborative, Investigative Recombinant DNA Technology Course with Laboratory

    Science.gov (United States)

    Pezzementi, Leo; Johnson, Joy F.

    2002-01-01

    A recombinant DNA technology course was designed to promote contextual, collaborative, inquiry-based learning of science where students learn from one another and have a sense of ownership of their education. The class stressed group presentations and critical reading and discussion of scientific articles. The laboratory consisted of two research…

  5. The many facets of homologous recombination at telomeres

    Directory of Open Access Journals (Sweden)

    Clémence Claussin

    2015-07-01

    Full Text Available The ends of linear chromosomes are capped by nucleoprotein structures called telomeres. A dysfunctional telomere may resemble a DNA double-strand break (DSB, which is a severe form of DNA damage. The presence of one DSB is sufficient to drive cell cycle arrest and cell death. Therefore cells have evolved mechanisms to repair DSBs such as homologous recombination (HR. HR-mediated repair of telomeres can lead to genome instability, a hallmark of cancer cells, which is why such repair is normally inhibited. However, some HR-mediated processes are required for proper telomere function. The need for some recombination activities at telomeres but not others necessitates careful and complex regulation, defects in which can lead to catastrophic consequences. Furthermore, some cell types can maintain telomeres via telomerase-independent, recombination-mediated mechanisms. In humans, these mechanisms are called alternative lengthening of telomeres (ALT and are used in a subset of human cancer cells. In this review, we summarize the different recombination activities occurring at telomeres and discuss how they are regulated. Much of the current knowledge is derived from work using yeast models, which is the focus of this review, but relevant studies in mammals are also included.

  6. Theory of a cw supersonic nitrogen recombination laser

    International Nuclear Information System (INIS)

    Quasi-two dimensional model calculations show the possibility to realize a cw atomic nitrogen laser, pumped by the recombination process in rapidly expanded plasma flows. Sufficient gain for lasing is demontrated for stagnation conditions of 13 000 00-1 can be attained. The model is described and some selected results are presented. The effect of the electron heat conduction is discussed

  7. Activity of recombinant factor VIIa under different conditions in vitro

    DEFF Research Database (Denmark)

    Bladbjerg, Else-Marie; Jespersen, Jørgen

    2008-01-01

    Recombinant activated factor VII (NovoSeven; Novo Nordisk A/S, Måløv, Denmark) is an effective drug for treatment of bleeding in patients with haemophilia A or B and inhibitors. Little is known about physiological conditions influencing the efficacy of recombinant activated factor VII. We...... investigated the in-vitro effects of pH, temperature, and haemodilution on the activity of recombinant activated factor VII. Samples from eight healthy volunteers were spiked with recombinant activated factor VII (final concentration 1.7 microg/ml) and adjusted to pH 6.0, 6.5, 7.0, and 7.4 or analysed at 30...... activity in plasma. Significant effects of pH were observed for clotting time, clot formation time, maximum clot firmness, and factor VII coagulant activity in the direction of longer clot formation times and less firm clots with decreasing pH. Temperature had significant effects on clotting time, clot...

  8. Metabolic adaptation in transplastomic plants massively accumulating recombinant proteins.

    Directory of Open Access Journals (Sweden)

    Julia Bally

    Full Text Available BACKGROUND: Recombinant chloroplasts are endowed with an astonishing capacity to accumulate foreign proteins. However, knowledge about the impact on resident proteins of such high levels of recombinant protein accumulation is lacking. METHODOLOGY/PRINCIPAL FINDINGS: Here we used proteomics to characterize tobacco (Nicotiana tabacum plastid transformants massively accumulating a p-hydroxyphenyl pyruvate dioxygenase (HPPD or a green fluorescent protein (GFP. While under the conditions used no obvious modifications in plant phenotype could be observed, these proteins accumulated to even higher levels than ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco, the most abundant protein on the planet. This accumulation occurred at the expense of a limited number of leaf proteins including Rubisco. In particular, enzymes involved in CO(2 metabolism such as nuclear-encoded plastidial Calvin cycle enzymes and mitochondrial glycine decarboxylase were found to adjust their accumulation level to these novel physiological conditions. CONCLUSIONS/SIGNIFICANCE: The results document how protein synthetic capacity is limited in plant cells. They may provide new avenues to evaluate possible bottlenecks in recombinant protein technology and to maintain plant fitness in future studies aiming at producing recombinant proteins of interest through chloroplast transformation.

  9. Recent advances in yeast molecular biology: recombinant DNA. [Lead abstract

    Energy Technology Data Exchange (ETDEWEB)

    1982-09-01

    Separate abstracts were prepared for the 25 papers presented at a workshop focusing on chromosomal structure, gene regulation, recombination, DNA repair, and cell type control, that have been obtained by experimental approaches incorporating the new technologies of yeast DNA transformation, molecular cloning, and DNA sequence analysis. (KRM)

  10. Yeast Hosts for the Production of Recombinant Laccases: A Review

    Czech Academy of Sciences Publication Activity Database

    Antošová, Zuzana; Sychrová, Hana

    2016-01-01

    Roč. 58, č. 2 (2016), s. 93-116. ISSN 1073-6085 R&D Projects: GA TA ČR(CZ) TA01011461 Institutional support: RVO:67985823 Keywords : laccase * yeasts * heterologous expression * recombinant * expression optimization Subject RIV: EE - Microbiology, Virology Impact factor: 1.876, year: 2014

  11. Recombineering using RecET from Pseudomonas syringae

    Science.gov (United States)

    Here we report the identification of functions that promote genomic recombination of linear DNA introduced into Pseudomonas cells by electroporation. The genes encoding these functions were identified in Pseudomonas syringae pv. syringae B728a based on similarity to the lambda Red Exo/Beta and RecE...

  12. Review of literature on catalytic recombination of hydrogen--oxygen

    International Nuclear Information System (INIS)

    The results are reported of a literature search for information concerning the heterogeneous, gas phase, catalytic hydrogen-oxygen recombination. Laboratory scale experiments to test the performance of specific metal oxide catalysts under conditions simulating the atmosphere within a nuclear reactor containment vessel following a loss-of-coolant blowdown accident are suggested

  13. EFFECT OF RECOMBINANT AEA-TMOF ON HELIOTHIS VIRESCENCE

    Science.gov (United States)

    Trypsin biosynthesis in H. virescens and larval growth (Weight gain) were followed after feeding 1st and 2nd instar larvae recombinant Pichia pastoris synthesizing TMOF in artificial diet for 7 days. Inhibition of 32% and 22.3% in weight gain was noted in 1st and 2nd instars, respectively, as compar...

  14. Soft X-ray bremsstrahlung and recombination radiation

    International Nuclear Information System (INIS)

    This report contains the theoretical background and computer codes for the calculation of soft X-ray bremsstrahlung and recombination radiation. These calculations are then used to calculate the effective Z of a plasma from the measured enhancement of the continuum radiation over that of pure hydrogen bremsstrahlung

  15. Development of an Aeromonas hydrophila recombinant extracellular protease vaccine.

    Science.gov (United States)

    Wu, Lei; Jiang, Ya-nan; Tang, Qian; Lin, Hui-xing; Lu, Cheng-ping; Yao, Huo-chun

    2012-01-01

    Aeromonas hydrophila (Ah) exists widely in the aquatic environment and infects a variety of animals. Extracellular protease (EPR) is an important protective antigen that induces a specific antibody response to resist Ah infection. In this study, two genes encoding extracellular protease epr2 and epr3 were linked within the expression vector pET32a to construct a recombinant pET-epr2-3 plasmid. The immunogenicity of the fusion protein epr2-3 was investigated as a subunit vaccine in ICR mice. The recombinant epr2-3 protein induced the production of high antibody titers. The survival rate against homogenous Ah J-1 challenge was significantly higher in the epr2-3 vaccinated group (≥80%) compared with the inactivated Ah vaccinated group and the challenge control group (P < 0.01), thus indicating that the recombinant epr2-3 protein provided significant protection against Ah infection. Therefore, the recombinant epr2-3 is a promising candidate for development as a vaccine against Ah infections. PMID:22874879

  16. Experimental studies on catalytic hydrogen recombiners for light water reactors

    International Nuclear Information System (INIS)

    In the course of core melt accidents in nuclear power plants a large amount of hydrogen can be produced and form an explosive or even detonative gas mixture with aerial oxygen in the reactor building. In the containment atmosphere of pressurized water reactors hydrogen combines a phlogistically with the oxygen present to form water vapor even at room temperature. In the past, experimental work conducted at various facilities has contributed little or nothing to an understanding of the operating principles of catalytic recombiners. Hence, the purpose of the present study was to conduct detailed investigations on a section of a recombiner essentially in order to deepen the understanding of reaction kinetics and heat transport processes. The results of the experiments presented in this dissertation form a large data base of measurements which provides an insight into the processes taking place in recombiners. The reaction-kinetic interpretation of the measured data confirms and deepens the diffusion theory - proposed in an earlier study. Thus it is now possible to validate detailed numeric models representing the processes in recombiners. Consequently the present study serves to broaden and corroborate competence in this significant area of reactor technology. In addition, the empirical knowledge thus gained may be used for a critical reassessment of previous numeric model calculations. (orig.)

  17. Meiotic sister chromatid cohesion and recombination in two filamentous fungi

    NARCIS (Netherlands)

    Heemst, van D.

    2000-01-01

    Homologous recombination and sister chromatid cohesion play important roles in the maintenance of genome integrity and the fidelity of chromosome segregation in mitosis and meiosis. Within the living cell, the integrity of the DNA is threatened by various factors that cause DNA-lesions, of which DNA

  18. Modelling of the aerosol deposition in a hydrogen catalytic recombiner

    Energy Technology Data Exchange (ETDEWEB)

    Vendel, J.; Studer, E.; Zavaleta, P. [Inst. de Protection et de Surete Nucleaire, Dept. de Prevention et d' Etudes des Accidents, Gif-sur-Yvette Cedex (France); Hadida, Ph. [Quasar Informatique, Paris (France)

    1997-03-01

    Catalytic recombiners are used to remove the hydrogen released in case of a severe accident in a nuclear power plant, so as to reduce the risk of deflagration or detonation. H{sub 2}PAR experiments are carried out to precise the behaviour of recombiners in term of poisoning by aerosols. Firstly, some calculations have been done with the Trio-EF code to assess the structure of convection loops in the experimental tent. We note that when the recombiner is active, it may have a strong influence on the flow inside the tent and may even interact with an other heat source such as a furnace. In the second part, we study the deposition of aerosols on catalytic plates for a given recombiner, when it is active or passive. We list the different mechanisms and quantify them by introducing the deposition velocity. In fact, thermophoresis appears to be the main mechanism, compared to brownian diffusion or difrusiophoresis, which governs aerosols deposition. It favours deposition on <> plates and acts against it for <> plates. (author)

  19. Modelling of the aerosol deposition in a hydrogen catalytic recombiner

    International Nuclear Information System (INIS)

    Catalytic recombiners are used to remove the hydrogen released in case of a severe accident in a nuclear power plant, so as to reduce the risk of deflagration or detonation. H2PAR experiments are carried out to precise the behaviour of recombiners in term of poisoning by aerosols. Firstly, some calculations have been done with the Trio-EF code to assess the structure of convection loops in the experimental tent. We note that when the recombiner is active, it may have a strong influence on the flow inside the tent and may even interact with an other heat source such as a furnace. In the second part, we study the deposition of aerosols on catalytic plates for a given recombiner, when it is active or passive. We list the different mechanisms and quantify them by introducing the deposition velocity. In fact, thermophoresis appears to be the main mechanism, compared to brownian diffusion or difrusiophoresis, which governs aerosols deposition. It favours deposition on > plates and acts against it for > plates. (author)

  20. Links between replication, recombination and genome instability in eukaryotes

    OpenAIRE

    Flores-Rozas, Hernan; Kolodner, Richard D.

    2000-01-01

    Double-strand breaks in DNA can be repaired by homologous recombination including break-induced replication. In this reaction, the end of a broken DNA invades an intact chromosome and primes DNA replication resulting in the synthesis of an intact chromosome. Break-induced replication has also been suggested to cause different types of genome rearrangements.

  1. Recent advances in yeast molecular biology: recombinant DNA

    International Nuclear Information System (INIS)

    Separate abstracts were prepared for the 25 papers presented at a workshop focusing on chromosomal structure, gene regulation, recombination, DNA repair, and cell type control, that have been obtained by experimental approaches incorporating the new technologies of yeast DNA transformation, molecular cloning, and DNA sequence analysis

  2. (Studies of autoionizing states relevant to dielectronic recombination. Final report)

    International Nuclear Information System (INIS)

    Laser spectroscopy experiments on autoionizing states of alkaline earth atoms allow the inverse process, dielectronic recombination, to be studied in great detail under controlled and variable conditions. The research is also relevant to problems in physical chemistry involving excited molecules, and it has helped to clarify the physical processes of zero kinetic energy electron spectroscopy and coherent control

  3. Analysis of Dibenzothiophene Desulfurization in a Recombinant Pseudomonas putida Strain▿

    OpenAIRE

    Calzada, Javier; Zamarro, María T.; Alcón, A.; Santos, Victoria E.; Díaz, Eduardo; García, José L.; García-Ochoa, Félix

    2008-01-01

    Biodesulfurization was monitored in a recombinant Pseudomonas putida CECT5279 strain. DszB desulfinase activity reached a sharp maximum at the early exponential phase, but it rapidly decreased at later growth phases. A model two-step resting-cell process combining sequentially P. putida cells from the late and early exponential growth phases was designed to significantly increase biodesulfurization.

  4. Recuperative thermal recombining system for handling loss of coolant

    International Nuclear Information System (INIS)

    A recycle loop method and recuperative heating system is provided for thermally recombining hydrogen and oxygen, such as may be desired in connection with a dissociated gas stream from a containment vessel for a nuclear reactor under loss of coolant accident conditions. The dissociated charge stream is preferably heated by indirect heat exchange with a resulting water vapor containing combined stream to effect heat conservation and, also preferably, the recuperative heat exchange operation and the high temperature recombining reaction are carried out in a unitary zone incorporating electrical, non-flame, heat input means. A particular feature of the present system resides in having the recycle of a portion of the resulting combined stream from the recombiner section pass into admixture with the hydrogen-oxygen containing charge stream to preclude an explosive condition and further having the quantity of such recycle regulated responsive to a temperature differential being measured across the recombiner zone as an indication of the oxygen level in such charge stream

  5. Recombination facilitates neofunctionalization of duplicate genes via originalization

    Directory of Open Access Journals (Sweden)

    Huang Ren

    2010-06-01

    Full Text Available Abstract Background Recently originalization was proposed to be an effective way of duplicate-gene preservation, in which recombination provokes the high frequency of original (or wild-type allele on both duplicated loci. Because the high frequency of wild-type allele might drive the arising and accumulating of advantageous mutation, it is hypothesized that recombination might enlarge the probability of neofunctionalization (Pneo of duplicate genes. In this article this hypothesis has been tested theoretically. Results Results show that through originalization recombination might not only shorten mean time to neofunctionalizaiton, but also enlarge Pneo. Conclusions Therefore, recombination might facilitate neofunctionalization via originalization. Several extensive applications of these results on genomic evolution have been discussed: 1. Time to nonfunctionalization can be much longer than a few million generations expected before; 2. Homogenization on duplicated loci results from not only gene conversion, but also originalization; 3. Although the rate of advantageous mutation is much small compared with that of degenerative mutation, Pneo cannot be expected to be small.

  6. A Mechanistic Model of a Passive Autocatalytic Hydrogen Recombiner

    Directory of Open Access Journals (Sweden)

    Rożeń Antoni

    2015-03-01

    Full Text Available : A passive autocatalytic hydrogen recombiner (PAR is a self-starting device, without operator action or external power input, installed in nuclear power plants to remove hydrogen from the containment building of a nuclear reactor. A new mechanistic model of PAR has been presented and validated by experimental data and results of Computational Fluid Dynamics (CFD simulations. The model allows to quickly and accurately predict gas temperature and composition, catalyst temperature and hydrogen recombination rate. It is assumed in the model that an exothermic recombination reaction of hydrogen and oxygen proceeds at the catalyst surface only, while processes of heat and mass transport occur by assisted natural and forced convection in non-isothermal and laminar gas flow conditions in vertical channels between catalyst plates. The model accounts for heat radiation from a hot catalyst surface and has no adjustable parameters. It can be combined with an equation of chimney draft and become a useful engineering tool for selection and optimisation of catalytic recombiner geometry.

  7. Genetic recombination in Actinoplanes brasiliensis by protoplast fusion.

    OpenAIRE

    Palleroni, N. J.

    1983-01-01

    Protoplast formation, fusion, and cell regeneration have been achieved with mutant strains of Actinoplanes brasiliensis. Three-, four-, and five-factor crosses have shown genetic recombination among the markers, and a five-factor cross is analyzed and discussed. Possibilities of using protoplast fusion for gene mapping and strain improvement are suggested.

  8. Recombination methods for boron neutron capture therapy dosimetry

    International Nuclear Information System (INIS)

    The radiation effects of boron neutron capture therapy (BNCT) are associated with four-dose-compartment radiation field - boron dose (from 10B(n,α)7Li) reaction), proton dose from 14N(n,p)14C reaction, neutron dose (mainly fast and epithermal neutrons) and gamma-ray dose (external and from capture reaction 1H(n,γ)2D). Because of this the relation between the absorbed dose and the biological effects is very complex and all the above mentioned absorbed dose components should be determined. From this point of view, the recombination chambers can be very useful instruments for characterization of the BNCT beams. They can be used for determination of gamma and high-LET dose components for the characterization of radiation quality of mixed radiation fields by recombination microdosimetric method (RMM). In present work, a graphite high-pressure recombination chamber filled with nitrogen, 10BF3 and tissue equivalent gas was used for studies on application of RMM for BNCT dosimetry. The use of these gases or their mixtures opens a possibility to design a recombination chamber for determination of the dose fractions due to gamma radiation, fast neutrons, neutron capture on nitrogen and high LET particles from (n,10B) reaction in simulated tissue with different content of 10B. (author)

  9. Insertion DNA Accelerates Meiotic Interchromosomal Recombination in Arabidopsis thaliana.

    Science.gov (United States)

    Sun, Xiao-Qin; Li, Ding-Hong; Xue, Jia-Yu; Yang, Si-Hai; Zhang, Yan-Mei; Li, Mi-Mi; Hang, Yue-Yu

    2016-08-01

    Nucleotide insertions/deletions are ubiquitous in eukaryotic genomes, and the resulting hemizygous (unpaired) DNA has significant, heritable effects on adjacent DNA. However, little is known about the genetic behavior of insertion DNA. Here, we describe a binary transgenic system to study the behavior of insertion DNA during meiosis. Transgenic Arabidopsis lines were generated to carry two different defective reporter genes on nonhomologous chromosomes, designated as "recipient" and "donor" lines. Double hemizygous plants (harboring unpaired DNA) were produced by crossing between the recipient and the donor, and double homozygous lines (harboring paired DNA) via self-pollination. The transfer of the donor's unmutated sequence to the recipient generated a functional β-glucuronidase gene, which could be visualized by histochemical staining and corroborated by polymerase chain reaction amplification and sequencing. More than 673 million seedlings were screened, and the results showed that meiotic ectopic recombination in the hemizygous lines occurred at a frequency  >6.49-fold higher than that in the homozygous lines. Gene conversion might have been exclusively or predominantly responsible for the gene correction events. The direct measurement of ectopic recombination events provided evidence that an insertion, in the absence of an allelic counterpart, could scan the entire genome for homologous counterparts with which to pair. Furthermore, the unpaired (hemizygous) architectures could accelerate ectopic recombination between itself and interchromosomal counterparts. We suggest that the ectopic recombination accelerated by hemizygous architectures may be a general mechanism for interchromosomal recombination through ubiquitously dispersed repeat sequences in plants, ultimately contributing to genetic renovation and eukaryotic evolution. PMID:27189569

  10. Ion-electron recombination in merged-beams experiments

    International Nuclear Information System (INIS)

    In the present thesis, studies of recombination processes applying the technique of merged beams of fast ions and electrons are described. The main advantage of this technique is that the low relative velocity of ions and electrons necessary for these investigations can be achieved, at the same time as the velocity of the ions relative to the molecules of the residual gas is high. The high ion velocity leads to a very low reaction cross section for the leading contribution to the background signal, the capture of electrons in collisions with residual gas molecules. The experimental technique is described, emphasizing the electron beam velocity distribution and its relation to the energy resolution of the experiments. The presentation of the process of electron cooling is aimed at introducing this process as a tool for merged-beams experiments in storage rings rather than investigating the process itself. The non-resonant process of radiative recombination for non-fully stripped ions, showing evidence of incomplete screening is presented. Experimental investigation of dielectronic recombination is presented. Results of measurements of this process for He-like ions form the Aarhus single-pass experiment and the Heidelberg storage ring experiment are compared. Recombination is reduced from being the aim of the investigation to being a tool for high-precision measurements of the lifetimes of the 1s2s 3S metastable states of HE-like ions of boron, carbon, and nitrogen, performed at the Heidelberg storage ring. The experiment is concerned with the process of dissociative recombination of molecular hydrogen ions. The discussion of this experiment emphasizes the distribution of population on the different vibrational levels of the ions in the initial state. In particular, a laser photo-dissociation technique was introduced to reduce the number of initial levels in the experiment. (EG) 24 refs

  11. Effective conductance method for the primordial recombination spectrum

    Science.gov (United States)

    Ali-Haïmoud, Yacine

    2013-01-01

    As atoms formed for the first time during primordial recombination, they emitted bound-bound and free-bound radiation leading to spectral distortions to the cosmic microwave background. These distortions might become observable in the future with high-sensitivity spectrometers, and provide a new window into physical conditions in the early universe. The standard multilevel atom method habitually used to compute the recombination spectrum is computationally expensive, impeding a detailed quantitative exploration of the information contained in spectral distortions thus far. In this work it is shown that the emissivity in optically thin allowed transitions can be factored into a computationally expensive but cosmology-independent part and a computationally cheap, cosmology-dependent part. The slow part of the computation consists in pre-computing temperature-dependent effective “conductances,” linearly relating line or continuum intensity to departures from Saha equilibrium of the lowest-order excited states (2s and 2p), that can be seen as “voltages.” The computation of these departures from equilibrium as a function of redshift is itself very fast, thanks to the effective multilevel atom method introduced in an earlier work. With this factorization, the recurring cost of a single computation of the recombination spectrum is only a fraction of a second on a standard laptop, more than four orders of magnitude shorter than standard computations. The spectrum from helium recombination can be efficiently computed in an identical way, and a fast code computing the full primordial recombination spectrum with this method will be made publicly available soon.

  12. Recombination in the human Pseudoautosomal region PAR1.

    Directory of Open Access Journals (Sweden)

    Anjali G Hinch

    2014-07-01

    Full Text Available The pseudoautosomal region (PAR is a short region of homology between the mammalian X and Y chromosomes, which has undergone rapid evolution. A crossover in the PAR is essential for the proper disjunction of X and Y chromosomes in male meiosis, and PAR deletion results in male sterility. This leads the human PAR with the obligatory crossover, PAR1, to having an exceptionally high male crossover rate, which is 17-fold higher than the genome-wide average. However, the mechanism by which this obligatory crossover occurs remains unknown, as does the fine-scale positioning of crossovers across this region. Recent research in mice has suggested that crossovers in PAR may be mediated independently of the protein PRDM9, which localises virtually all crossovers in the autosomes. To investigate recombination in this region, we construct the most fine-scale genetic map containing directly observed crossovers to date using African-American pedigrees. We leverage recombination rates inferred from the breakdown of linkage disequilibrium in human populations and investigate the signatures of DNA evolution due to recombination. Further, we identify direct PRDM9 binding sites using ChIP-seq in human cells. Using these independent lines of evidence, we show that, in contrast with mouse, PRDM9 does localise peaks of recombination in the human PAR1. We find that recombination is a far more rapid and intense driver of sequence evolution in PAR1 than it is on the autosomes. We also show that PAR1 hotspot activities differ significantly among human populations. Finally, we find evidence that PAR1 hotspot positions have changed between human and chimpanzee, with no evidence of sharing among the hottest hotspots. We anticipate that the genetic maps built and validated in this work will aid research on this vital and fascinating region of the genome.

  13. Recombination in the human Pseudoautosomal region PAR1.

    Science.gov (United States)

    Hinch, Anjali G; Altemose, Nicolas; Noor, Nudrat; Donnelly, Peter; Myers, Simon R

    2014-07-01

    The pseudoautosomal region (PAR) is a short region of homology between the mammalian X and Y chromosomes, which has undergone rapid evolution. A crossover in the PAR is essential for the proper disjunction of X and Y chromosomes in male meiosis, and PAR deletion results in male sterility. This leads the human PAR with the obligatory crossover, PAR1, to having an exceptionally high male crossover rate, which is 17-fold higher than the genome-wide average. However, the mechanism by which this obligatory crossover occurs remains unknown, as does the fine-scale positioning of crossovers across this region. Recent research in mice has suggested that crossovers in PAR may be mediated independently of the protein PRDM9, which localises virtually all crossovers in the autosomes. To investigate recombination in this region, we construct the most fine-scale genetic map containing directly observed crossovers to date using African-American pedigrees. We leverage recombination rates inferred from the breakdown of linkage disequilibrium in human populations and investigate the signatures of DNA evolution due to recombination. Further, we identify direct PRDM9 binding sites using ChIP-seq in human cells. Using these independent lines of evidence, we show that, in contrast with mouse, PRDM9 does localise peaks of recombination in the human PAR1. We find that recombination is a far more rapid and intense driver of sequence evolution in PAR1 than it is on the autosomes. We also show that PAR1 hotspot activities differ significantly among human populations. Finally, we find evidence that PAR1 hotspot positions have changed between human and chimpanzee, with no evidence of sharing among the hottest hotspots. We anticipate that the genetic maps built and validated in this work will aid research on this vital and fascinating region of the genome. PMID:25033397

  14. Constraints contributed by chromatin looping limit recombination targeting during Ig class switch recombination.

    Science.gov (United States)

    Feldman, Scott; Achour, Ikbel; Wuerffel, Robert; Kumar, Satyendra; Gerasimova, Tatiana; Sen, Ranjan; Kenter, Amy L

    2015-03-01

    Engagement of promoters with distal elements in long-range looping interactions has been implicated in regulation of Ig class switch recombination (CSR). The principles determining the spatial and regulatory relationships among Igh transcriptional elements remain poorly defined. We examined the chromosome conformation of C region (CH) loci that are targeted for CSR in a cytokine-dependent fashion in mature B lymphocytes. Germline transcription (GLT) of the γ1 and ε CH loci is controlled by two transcription factors, IL-4-inducible STAT6 and LPS-activated NF-κB. We showed that although STAT6 deficiency triggered loss of GLT, deletion of NF-κB p50 abolished both GLT and γ1 locus:enhancer looping. Thus, chromatin looping between CH loci and Igh enhancers is independent of GLT production and STAT6, whereas the establishment and maintenance of these chromatin contacts requires NF-κB p50. Comparative analysis of the endogenous γ1 locus and a knock-in heterologous promoter in mice identified the promoter per se as the interactive looping element and showed that transcription elongation is dispensable for promoter/enhancer interactions. Interposition of the LPS-responsive heterologous promoter between the LPS-inducible γ3 and γ2b loci altered GLT expression and essentially abolished direct IgG2b switching while maintaining a sequential μ→γ3→γ2b format. Our study provides evidence that promoter/enhancer looping interactions can introduce negative constraints on distal promoters and affect their ability to engage in germline transcription and determine CSR targeting. PMID:25624452

  15. Correlation of the activities of protein C,antithrombin and coagulation factor Ⅷ with the treatment of lung cancer with pulmonary embolism%蛋白 C、抗凝血酶及凝血因子Ⅷ活性变化与肺癌合并肺栓塞后治疗的关系

    Institute of Scientific and Technical Information of China (English)

    陈环; 张鹏; 刘军锋

    2014-01-01

    Objective To investigate the correlation of the activities of protein C(PC),antithrombin(AT)and coagulation factor Ⅷ(FⅧ)with the treatment of lung cancer with pulmonary embolism(PE).Methods A total of 98 patients with lung cancer and PE were enrolled as lung cancer with PE group.A total of 1 00 patients with lung cancer were enrolled as lung cancer group.Their sex and age were recorded,and lipoprotein(a)[Lp(a)],total cholesterol (TC),triglyceride (TG),C-reactive protein(CRP),thrombin time(TT),platelet (PLT)and fibrinogen(Fbg)in the 2 groups were determined,respectively.PC,AT,FⅧ and D-dimer were determined in lung cancer with PE group after 5-7 d of treatment.Logistic regression analysis was used to analyze the factors influencing coagulation-fibrinolysis after 5-7 d of treatment in lung cancer with PE group.The receiver operating characteristic(ROC)curve was used to analyze the diagnostic efficiency of these factors.Results Lp (a),TC,TG and TT in lung cancer with PE group were significantly higher than those in lung cancer group (P 0.90.Conclusions The influence of PC,AT and FⅧ on coagulation-fibrinolysis should be concerned in midterm treatment of lung cancer with PE,and their activities can be used to assess the therapeutic efficiency and treatment program in a given period.%目的:探讨蛋白C(PC)、抗凝血酶(AT)及凝血因子Ⅷ(FⅧ)活性变化与肺癌合并肺血栓栓塞[简称肺栓塞(PE)]后治疗的关系。方法选择肺癌合并 PE 患者(肺癌+PE 组)98例及肺癌患者(肺癌组)100例。记录两组性别、年龄并检测脂蛋白(a)[Lp(a)]、总胆固醇(TC)、甘油三酯(TG)、C 反应蛋白(CRP)、凝血酶时间(TT)、血小板数量(PLT)、纤维蛋白原(Fbg)等指标。检测肺癌+PE 组治疗5~7 d 及肺癌组入院时的 PC、AT、FⅧ、D-二聚体水平。应用 Logistic 回归分析肺癌合并 PE 后治疗5~7 d 凝血-纤溶状态的影响因素,

  16. Clinical Significance of von Willebrand Factor and Antithrombin in Diabetes Mellitus with Retinopathy%血管性血友病因子与抗凝血酶在糖尿病视网膜病变中的临床意义

    Institute of Scientific and Technical Information of China (English)

    张鹏; 汤荣华

    2012-01-01

    目的 探讨糖尿病微血管视网膜病变患者血管性血友病因子(vWF)、抗凝血酶(AT)的变化及临床意义.方法 将100例2型糖尿病患者分为两组,糖尿病无微血管视网膜病变并发症组53例,糖尿病微血管视网膜病变并发症组47例,设健康人群对照组50例.所有人群入院或体检时即采集静脉血,进行vWF:Ag、AT:A检测.结果 2型糖尿病无微血管视网膜病变并发症组患者血浆vWF:Ag含量较正常对照组增高(P<0.05),2型糖尿病微血管视网膜病变并发症组患者血浆vWF:Ag含量与2型糖尿病无微血管视网膜病变并发症组及正常对照组相比有显著性差异(P<0.05);且2型糖尿病微血管视网膜病变并发症组中背景性病变和增殖性病变患者血浆vWF:Ag含量比较有显著性差异(P<0.05).2型糖尿病无微血管视网膜病变并发症组患者血浆AT活性与正常对照组相比无显著性差异(P>0.05),2型糖尿病微血管视网膜病变并发症组患者血浆AT活性与2型糖尿病无微血管视网膜病变并发症组及正常对照组相比有显著性差异(P<0.05);且2型糖尿病微血管视网膜病变并发症组中背景性病变和增殖性病变患者血浆AT活性比较有显著性差异(P<0.05).结论 血浆vWF:Ag、AT:A的变化与糖尿病微血管视网膜病变的发生、发展有密切关系,监测其水平与活性对糖尿病微血管并发症的治疗和预防有重要的临床意义.%Objective To explore the changes of von Willebrand factor(vWF) and antithrombin(AT) in diabetic patients with retinopathy and its clinical implications. Methods 100 type 2 diabetes mellitus (T2DM) patients were divided into 2 groups,one group included 53 T2DM patients without retinopathy,another group included 47 T2DM patients with retinopathy, 50 healthy peoples were enrolled as control group. Venous blood was collected from all groups and vWF:Ag, AT; A were determined. Results The level of vWF;Ag in T2DM

  17. Correlations between recombination rate and intron distributions along chromosomes of C.elegans

    Institute of Scientific and Technical Information of China (English)

    Hong Li; Guoqing Liu; Xuhua Xia

    2009-01-01

    Generally speaking,the intron size positively correlates with recombination rate in Caenorhabditis elegans genome.Here,we analyze the correlations between recombination rate and some measures of different intron lengths so as to know whether the recombination influences the introns of different lengths in the same way.Results show that the correlation between the recombination rate and the percentage of short introns(<100 bp)is negative,but the correlation between the recombination rate and the percentage of introns that are larger than 500 bp is positive.Average intron length correlates positively with the recombination rate for introns whose length is in the range of 100-1000 bp.We speculate that the recombination mainly exerts impact on introns whose length ranges from 100-1000 bp.We also show that the average intron number per gene correlates negatively with the recombination rate.

  18. Productive homologous and non-homologous recombination of hepatitis C virus in cell culture

    DEFF Research Database (Denmark)

    Scheel, Troels K H; Galli, Andrea; Li, Yi-Ping; Mikkelsen, Lotte S; Gottwein, Judith M; Bukh, Jens

    2013-01-01

    Genetic recombination is an important mechanism for increasing diversity of RNA viruses, and constitutes a viral escape mechanism to host immune responses and to treatment with antiviral compounds. Although rare, epidemiologically important hepatitis C virus (HCV) recombinants have been reported...

  19. RNA Recombination Enhances Adaptability and Is Required for Virus Spread and Virulence.

    Science.gov (United States)

    Xiao, Yinghong; Rouzine, Igor M; Bianco, Simone; Acevedo, Ashley; Goldstein, Elizabeth Faul; Farkov, Mikhail; Brodsky, Leonid; Andino, Raul

    2016-04-13

    Mutation and recombination are central processes driving microbial evolution. A high mutation rate fuels adaptation but also generates deleterious mutations. Recombination between two different genomes may resolve this paradox, alleviating effects of clonal interference and purging deleterious mutations. Here we demonstrate that recombination significantly accelerates adaptation and evolution during acute virus infection. We identified a poliovirus recombination determinant within the virus polymerase, mutation of which reduces recombination rates without altering replication fidelity. By generating a panel of variants with distinct mutation rates and recombination ability, we demonstrate that recombination is essential to enrich the population in beneficial mutations and purge it from deleterious mutations. The concerted activities of mutation and recombination are key to virus spread and virulence in infected animals. These findings inform a mathematical model to demonstrate that poliovirus adapts most rapidly at an optimal mutation rate determined by the trade-off between selection and accumulation of detrimental mutations. PMID:27078068

  20. Roles of nonhomologous DNA end joining, V(D)J recombination, and class switch recombination in chromosomal translocations.

    Science.gov (United States)

    Lieber, Michael R; Yu, Kefei; Raghavan, Sathees C

    2006-09-01

    When a single double-strand break arises in the genome, nonhomologous DNA end joining (NHEJ) is a major pathway for its repair. When double-strand breaks arise at two nonhomologous sites in the genome, NHEJ also appears to be a major pathway by which the translocated ends are joined. The mechanism of NHEJ is briefly summarized, and alternative enzymes are also discussed. V(D)J recombination and class switch recombination are specialized processes designed to create double-strand DNA breaks at specific locations in the genomes of lymphoid cells. Sporadic Burkitt's lymphoma and myelomas can arise due to translocation of the c-myc gene into the Ig heavy chain locus during class switch recombination. In other lymphoid neoplasms, the RAG complex can create double-strand breaks that result in a translocation. Such RAG-generated breaks occur at very specific nucleotides that are directly adjacent to sequences that resemble canonical heptamer/nonamer sequences characteristic of normal V(D)J recombination. This occurs in some T cell leukemias and lymphomas. The RAG complex also appears capable of recognizing regions for their altered DNA structure rather than their primary sequence, and this may account for the action by RAGs at some chromosomal translocation sites, such as at the bcl-2 major breakpoint region in the follicular lymphomas that arise in B lymphocytes. PMID:16793349

  1. Effects of Supplementation of Various Medium Components on Chinese Hamster Ovary Cell Cultures Producing Recombinant Antibody

    OpenAIRE

    Kim, Do Yun; Lee, Joon Chul; Chang, Ho Nam; Oh, Duk Jae

    2005-01-01

    Thirteen vitamins, twenty amino acids, hormones, inorganic salts, and other chemical agents, which constitute typical serum-free media, were evaluated for the development of fortified medium to enhance cell growth and productivity of recombinant antibody in the cultures of the recombinant Chinese hamster ovary (rCHO) cells. Two different rCHO cell lines, rCHO-A producing recombinant antibodies against the human platelet and rCHO-B secreting recombinant antibodies against the S surface antigen...

  2. Similarity in Recombination Rate Estimates Highly Correlates with Genetic Differentiation in Humans

    OpenAIRE

    Laayouni, Hafid; Montanucci, Ludovica; Sikora, Martin, 1976-; Melé, Marta; Dall'Olio, Giovanni Marco, 1983-; Lorente-Galdós, Belén; McGee, Kate M; Graffelman, Jan; Awadalla, Philip; Bosch, Elena; Comas, David; Navarro, Arcadi; Calafell, Francesc; Casals, Ferran; Bertranpetit, Jaume

    2011-01-01

    Recombination varies greatly among species, as illustrated by the poor conservation of the recombination landscape between humans and chimpanzees. Thus, shorter evolutionary time frames are needed to understand the evolution of recombination. Here, we analyze its recent evolution in humans. We calculated the recombination rates between adjacent pairs of 636,933 common single-nucleotide polymorphism loci in 28 worldwide human populations and analyzed them in relation to genetic distances betwe...

  3. Dimer-atom-atom recombination in the universal four-boson system

    OpenAIRE

    Deltuva, A.

    2012-01-01

    The dimer-atom-atom recombination process in the system of four identical bosons with resonant interactions is studied. The description uses the exact Alt, Grassberger and Sandhas equations for the four-particle transition operators that are solved in the momentum-space framework. The dimer-dimer and atom-trimer channel contributions to the ultracold dimer-atom-atom recombination rate are calculated. The dimer-atom-atom recombination rate greatly exceeds the three-atom recombination rate.

  4. Determination of surface recombination velocities of organic monolayers on silicon through Kelvin probe

    OpenAIRE

    Alderman, Nicholas; Adib Ibrahim, Mohd; Danos, Lefteris; Martin C. Grossel; Markvart, Tom

    2013-01-01

    We report the determination of the surface recombination velocity of electron-hole pairs for silicon samples passivated with organic monolayers using the Kelvin probe. The recombination velocity was determined from the surface photovoltage and incident photon flux. By scanning of the Kelvin probe tip over the sample, the change in surface recombination velocity can be measured allowing recombination lifetime mapping. Organic monolayers with different chain lengths and exhibiting various recom...

  5. Bounds on the minimum number of recombination events in a sample history.

    OpenAIRE

    Myers, Simon R; Griffiths, Robert C.

    2003-01-01

    Recombination is an important evolutionary factor in many organisms, including humans, and understanding its effects is an important task facing geneticists. Detecting past recombination events is thus important; this article introduces statistics that give a lower bound on the number of recombination events in the history of a sample, on the basis of the patterns of variation in the sample DNA. Such lower bounds are appropriate, since many recombination events in the history are typically un...

  6. Sum rules for meson and baryon production in the quark recombination model

    International Nuclear Information System (INIS)

    A quark recombination model with quark distributions according to a generalized Kuti-Weisskopf model is used. Mesons are formed by v-s (valence-sea) and s-s recombination, baryons by vvv, vvs, vss and sss recombination. Sum rules for energy momentum concervation, baryon number, valence and sea quarks are shown to constrain the recombination parameters of the model significantly. The resulting model is consistent with experimental data. (author)

  7. Escherichia coli extract-catalyzed recombination in switch regions of mouse immunoglobulin genes.

    OpenAIRE

    Kataoka, T.; Takeda, S.; Honjo, T

    1983-01-01

    We have shown that Escherichia coli extracts catalyze recombination between mouse immunoglobulin mu and alpha genes inserted separately in lambda phage vectors carrying different genetic markers. Most of the recombination sites in the inserts are located in the switch regions of the heavy chain genes, as previously found in the expressed genes of myeloma cells. The recombination took place at relatively high frequency (10(-4)). The recombinational system in E. coli or lambda phage seems to pr...

  8. Trends in the electric field enhancement of dielectronic recombination cross sections

    International Nuclear Information System (INIS)

    The effect of external electric fields on the dielectronic recombination cross section of selected ions has been studied in the configuration-average, distorted wave approximation. By applying the linear-Stark approximation to the doubly-excited Rydberg states formed from resonant recombination, we examine the systematics of field-mixing effects on dielectronic recombination and determine the maximum field enhancement of dielectronic recombination cross sections. 8 references, 6 figures, 3 tables

  9. Ad 2.0: a novel recombineering platform for high-throughput generation of tailored adenoviruses

    OpenAIRE

    Mück-Häusl, Martin; Solanki, Manish; Zhang, Wenli; Ruzsics, Zsolt; Ehrhardt, Anja

    2015-01-01

    Recombinant adenoviruses containing a double-stranded DNA genome of 26–45 kb were broadly explored in basic virology, for vaccination purposes, for treatment of tumors based on oncolytic virotherapy, or simply as a tool for efficient gene transfer. However, the majority of recombinant adenoviral vectors (AdVs) is based on a small fraction of adenovirus types and their genetic modification. Recombineering techniques provide powerful tools for arbitrary engineering of recombinant DNA. Here, we ...

  10. The effects of G418 on the growth and metabolism of recombinant mammalian cell lines

    OpenAIRE

    Yallop, Christopher Adam; Svendsen, Ivan

    2001-01-01

    It is widely reported that the growth of recombinant bacteria and yeast is adversely affected by increased metabolic load caused by the maintenance of plasmid copy number and recombinant protein expression. Reports suggest that recombinant mammalian systems are similarly affected by increased metabolic load. However, in comparison to bacterial systems relatively little information exists. It was the aim of this study to test the effects of recombinant gene expression on the growth and metabol...

  11. Fibroblast interleukin 1 beta: synergistic stimulation by recombinant interleukin 1 and tumor necrosis factor and posttranscriptional regulation.

    OpenAIRE

    Elias, J. A.; Reynolds, M M; Kotloff, R M; Kern, J A

    1989-01-01

    To understand the role fibroblasts play in mediating and amplifying the effects of inflammatory cytokines, we determined whether recombinant interleukin 1 (IL-1) and recombinant tumor necrosis factor (TNF), alone and in combination, stimulated fibroblasts to produce IL-1 beta. Recombinant IL-1 (alpha and beta) stimulated fibroblast IL-1 beta mRNA accumulation, whereas recombinant TNF did not. In addition, simultaneous stimulation with recombinant IL-1 (alpha or beta) and recombinant TNF resul...

  12. Intracellular transport of recombinant coronavirus spike proteins: implications for virus assembly

    NARCIS (Netherlands)

    Horzinek, M.C.; Vennema, H.; Heijnen, L.; Zijderveld, A.; Spaan, W.J.M.

    1990-01-01

    Coronavirus spike protein genes were expressed in vitro by using the recombinant vaccinia virus expression system. Recombinant spike proteins were expressed at the cell surface and induced cell fusion in a host-cell-dependent fashion. The intracellular transport of recombinant spike proteins was stu

  13. Overview of developments in the last 10-15 years in recombinant vaccines

    Science.gov (United States)

    This introductory talk will describe the various types of recombinant DNA vaccines that have been developed for the poultry industry. The talk will not discuss the efficacy of specific recombinant DNA vaccines. Instead, I will focus on describing how various recombinant vaccines are made and some ad...

  14. 21 CFR 878.4494 - Absorbable poly(hydroxybutyrate) surgical suture produced by recombinant DNA technology.

    Science.gov (United States)

    2010-04-01

    ... produced by recombinant DNA technology. 878.4494 Section 878.4494 Food and Drugs FOOD AND DRUG... recombinant DNA technology. (a) Identification. An absorbable poly(hydroxybutyrate) surgical suture is an...) Surgical Suture Produced by Recombinant DNA Technology.” For the availability of this guidance document...

  15. 21 CFR 528.1070 - Bc6 recombinant deoxyribonucleic acid construct.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Bc6 recombinant deoxyribonucleic acid construct... ANIMALS § 528.1070 Bc6 recombinant deoxyribonucleic acid construct. (a) Specifications and indications for use. Five copies of a human Bc6 recombinant deoxyribonucleic acid (rDNA) construct located at the...

  16. Study of electron recombination in liquid argon with the ICARUS TPC

    International Nuclear Information System (INIS)

    Electron recombination in liquid argon (LAr) is studied by means of charged particle tracks collected in various ICARUS liquid argon TPC prototypes. The dependence of the recombination on the particle stopping power has been fitted with a Birks functional dependence. The simulation of the process of electron recombination in Monte Carlo calculations is discussed. A quantitative comparison with previously published data is carried out

  17. DNA helicases in recombination and repair: construction of a delta uvrD delta helD delta recQ mutant deficient in recombination and repair.

    OpenAIRE

    Mendonca, V M; Klepin, H D; Matson, S W

    1995-01-01

    DNA helicases play pivotal roles in homologous recombination and recombinational DNA repair. They are involved in both the generation of recombinogenic single-stranded DNA ends and branch migration of synapsed Holliday junctions. Escherichia coli helicases II (uvrD), IV (helD), and RecQ (recQ) have all been implicated in the presynaptic stage of recombination in the RecF pathway. To probe for functional redundancy among these helicases, mutant strains containing single, double, and triple del...

  18. Recombinant cells that highly express chromosomally-integrated heterologous gene

    Science.gov (United States)

    Ingram, Lonnie O.; Ohta, Kazuyoshi; Wood, Brent E.

    2007-03-20

    Recombinant host cells are obtained that comprise (A) a heterologous, polypeptide-encoding polynucleotide segment, stably integrated into a chromosome, which is under transcriptional control of an endogenous promoter and (B) a mutation that effects increased expression of the heterologous segment, resulting in enhanced production by the host cells of each polypeptide encoded by that segment, relative to production of each polypeptide by the host cells in the absence of the mutation. The increased expression thus achieved is retained in the absence of conditions that select for cells displaying such increased expression. When the integrated segment comprises, for example, ethanol-production genes from an efficient ethanol producer like Zymomonas mobilis, recombinant Escherichia coli and other enteric bacterial cells within the present invention are capable of converting a wide range of biomass-derived sugars efficiently to ethanol.

  19. Proton to pion ratio at RHIC from dynamical quark recombination

    CERN Document Server

    Ayala, Alejandro; Paic, Guy; Toledo-Sanchez, Genaro

    2008-01-01

    We propose an scenario to study, from a dynamical point of view, the thermal recombination of quarks in the midsts of a relativistic heavy-ion collision. We coin the term dynamical quark recombination to refer to the process of quark-antiquark and three-quark clustering, to form mesons and baryons, respectively, as a function of energy density. Using the string-flip model we show that the probabilities to form such clusters differ. We apply these ideas to the calculation of the proton and pion spectra in a Bjorken-like scenario that incorporates the evolution of these probabilities with proper time and compute the proton to pion ratio, comparing to recent RHIC data at the highest energy. We show that for a standard choice of parameters, this ratio reaches one, though the maximum is very sensitive to the initial evolution proper time.

  20. Production of Recombinant Chemokines and Validation of Refolding.

    Science.gov (United States)

    Veldkamp, Christopher T; Koplinski, Chad A; Jensen, Davin R; Peterson, Francis C; Smits, Kaitlin M; Smith, Brittney L; Johnson, Scott K; Lettieri, Christina; Buchholz, Wallace G; Solheim, Joyce C; Volkman, Brian F

    2016-01-01

    The diverse roles of chemokines in normal immune function and many human diseases have motivated numerous investigations into the structure and function of this family of proteins. Recombinant chemokines are often used to study how chemokines coordinate the trafficking of immune cells in various biological contexts. A reliable source of biologically active protein is vital for any in vitro or in vivo functional analysis. In this chapter, we describe a general method for the production of recombinant chemokines and robust techniques for efficient refolding that ensure consistently high biological activity. Considerations for initiating development of protocols consistent with Current Good Manufacturing Practices (cGMPs) to produce biologically active chemokines suitable for use in clinical trials are also discussed. PMID:26921961

  1. Origins of the machinery of recombination and sex.

    Science.gov (United States)

    Cavalier-Smith, T

    2002-02-01

    Mutation plays the primary role in evolution that Weismann mistakenly attributed to sex. Homologous recombination, as in sex, is important for population genetics--shuffling of minor variants, but relatively insignificant for large-scale evolution. Major evolutionary innovations depend much more on illegitimate recombination, which makes novel genes by gene duplication and by gene chimaerisation--essentially mutational forces. The machinery of recombination and sex evolved in two distinct bouts of quantum evolution separated by nearly 3 Gy of stasis; I discuss their nature and causes. The dominant selective force in the evolution of recombination and sex has been selection for replicational fidelity and viability; without the recombination machinery, accurate reproduction, stasis, resistance to radical deleterious evolutionary change and preservation of evolutionary innovations would be impossible. Recombination proteins betray in their phylogeny and domain structure a key role for gene duplication and chimaerisation in their own origin. They arose about 3.8 Gy ago to enable faithful replication and segregation of the first circular DNA genomes in precellular ancestors of Gram-negative eubacteria. Then they were recruited and modified by selfish genetic parasites (viruses; transposons) to help them spread from host to host. Bacteria differ fundamentally from eukaryotes in that gene transfer between cells, whether incidental to their absorptive feeding on DNA and virus infection or directly by plasmids, involves only genomic fragments. This was radically changed by the neomuran revolution about 850 million years ago when a posibacterium evolved into the thermophilic cenancestor of eukaryotes and archaebacteria (jointly called neomurans), radically modifying or substituting its DNA-handling enzymes (those responsible for transcription as well as for replication, repair and recombination) as a coadaptive consequence of the origin of core histones to stabilise its

  2. Steady-state photoluminescent excitation characterization of semiconductor carrier recombination

    International Nuclear Information System (INIS)

    Photoluminescence excitation spectroscopy is a contactless characterization technique that can provide valuable information about the surface and bulk recombination parameters of a semiconductor device, distinct from other sorts of photoluminescent measurements. For this technique, a temperature-tuned light emitting diode (LED) has several advantages over other light sources. The large radiation density offered by LEDs from near-infrared to ultraviolet region at a low cost enables efficient and fast photoluminescence measurements. A simple and inexpensive LED-based setup facilitates measurement of surface recombination velocity and bulk Shockley-Read-Hall lifetime, which are key parameters to assess device performance. Under the right conditions, this technique can also provide a contactless way to measure the external quantum efficiency of a solar cell

  3. Thermostimulated recombination processes in LiBaF3 crystals

    International Nuclear Information System (INIS)

    The creation of radiation defects in LiBaF3 crystals at 10 K and the processes of their thermostimulated recombination are investigated. The methods of optical absorption, thermal bleaching of color centers, thermostimulated luminescence and fractional glow technique are used. The radiation defects anneal in a multi-stage process accompanied with thermo-luminescence at 20, 46, 105, 130, 170, 210 and 270 K. Differences in the optical absorption spectra measured before and after the TSL peaks are obtained and recombination parameters are determined. The TSL peak at 20 K arises from the delocalization of H-centers. The presence of two TSL peaks related to VK-centers at 105 and 130 K indicates that 60 deg. and 90 deg. migration hops occur

  4. Insulin allergy treated with human insulin (recombinant DNA).

    Science.gov (United States)

    De Leeuw, I; Delvigne, C; Bekaert, J

    1982-01-01

    Two insulin-dependent diabetic subjects treated with pork and beef insulin during a period of 6 mo developed severe local reactions. Both patients had an important allergic history (asthma, urticaria, drug reactions, rhinitis). Skin-testing revealed type I allergy to beef and pork insulin. Specific IgE-insulin binding was demonstrated with both insulins. After negative skin testing with NPH Lilly human insulin (recombinant DNA), treatment was started with this compound and remained successful during a period of 6-9 mo. In one patient a local reaction occurred when regular human insulin (recombinant DNA) was added to NPH in order to obtain better control. Skin testing with regular human insulin was positive, but not with NPH human insulin alone. The mechanism of this phenomenon remains unsolved. PMID:6765530

  5. Transfer line from the PSB to the PS (recombination)

    CERN Multimedia

    1976-01-01

    After sequential ejection of 5 bunches from each of the 4 rings of the Booster (originally 800 MeV, now 1.4 GeV), the 4 batches are brought to the same vertical level, so as to form a string of 20 bunches, filling the circumference of the PS. This vertical "recombination" is performed in the transfer line, using vertical bending magnets, septa and kickers. Here we see the section where the beam from ring 4 (the top one) is brought down to the level of ring 3, and the beam from ring 1 up to the level of ring 2. Further downstream (to the right, outside this picture), level 2 is brought up to level 3, identical to that of the PS. After this original recombination scheme, other ways of combining the 4 beams, vertically and/or longitudinally, were developed and used in operation.

  6. Insights into epigenetic landscape of recombination-free regions.

    Science.gov (United States)

    Termolino, Pasquale; Cremona, Gaetana; Consiglio, Maria Federica; Conicella, Clara

    2016-06-01

    Genome architecture is shaped by gene-rich and repeat-rich regions also known as euchromatin and heterochromatin, respectively. Under normal conditions, the repeat-containing regions undergo little or no meiotic crossover (CO) recombination. COs within repeats are risky for the genome integrity. Indeed, they can promote non-allelic homologous recombination (NAHR) resulting in deleterious genomic rearrangements associated with diseases in humans. The assembly of heterochromatin is driven by the combinatorial action of many factors including histones, their modifications, and DNA methylation. In this review, we discuss current knowledge dealing with the epigenetic signatures of the major repeat regions where COs are suppressed. Then we describe mutants for epiregulators of heterochromatin in different organisms to find out how chromatin structure influences the CO rate and distribution. PMID:26801812

  7. IDENTIFICATION OF PATHOGENIC LEPTOSPIRES BY RECOMBINANT DNA PROBES

    Institute of Scientific and Technical Information of China (English)

    戴保民; 肖建国; 沈成义

    1994-01-01

    Early diagnosis of leptospirosis of pulmonary diffuse bernorrhage type (PDH) is of crucial importance in saving patients. To develop a sensitive and specific method for diagnvsis, a genonlic library of the main pathogen of PDH, L. interogans serovar lai strath 017, was constructed with the plasmid vector pUC9. Recmbinant plasmids which have hornologotLq fragments of pathogenic inptospires were screened from the bank. A recombinant plasmid.designated pCX7, could detect 1. 7 kb fragment of strain 017. 9. 0 kb of strain 601 and 30. 0 kb of strain Hebdo-maclis, respectively, without cross hybridization with nonpathogcnic leptospires such as L. biflexa strain Patoc 1 and Leptonema illini. The recombinant plasmid pCX7 could detect pathogenic leptospires which are the main pathogens endemic to Sichuan Province.

  8. Intragenic recombination in the CSR1 locus of Arabidopsis.

    Science.gov (United States)

    Mourad, G; Haughn, G; King, J

    1994-04-01

    Four classes of herbicides are known to inhibit plant acetolactate synthase (ALS). In Arabidopsis, ALS is encoded by a single gene, CSR1. The dominant csr1-1 allele encodes an ALS resistant to chlorsulfuron and triazolopyrimidine sulfonamide while the dominant csr1-2 allele encodes an ALS resistant to imazapyr and pyrimidyl-oxy-benzoate. The molecular distance between the point mutations in csr1-1 and csr1-2 is 1369 bp. Here we used multiherbicide resistance as a stringent selection to measure the intragenic recombination frequency between these two point mutations. We found this frequency to be 0.008 +/- 0.0028. The recombinant multiherbicide-resistant allele, csr1-4, provides an ideal marker for plant genetic transformation. PMID:8177214

  9. Commercialisation of a recombinant vaccine against Boophilus microplus.

    Science.gov (United States)

    Willadsen, P; Bird, P; Cobon, G S; Hungerford, J

    1995-01-01

    Increasingly, there is need for methods to control cattle tick (Boophilus microplus) infestations by the use of non-chemical technology. This need is brought about by a mixture of market forces and the failure or inadequacy of existing technology. A recombinant vaccine has now been developed against the tick. This vaccine relies on the uptake with the blood meal of antibody directed against a critical protein in the tick gut. The isolation of the vaccine antigen, Bm86, and its production as a recombinant protein is briefly described. The vaccine has been tested in the field, has been taken through the full registration process and is now in commercial use in Australia. A related development has occurred in Cuba. The potential for improvement of the current vaccine and for the development of similar vaccines against other haematophagous parasites is discussed. PMID:7784128

  10. Construction of recombinant DNA clone for bovine viral diarrhea virus

    International Nuclear Information System (INIS)

    Molecular cloning was carried out on the Danish strain of bovine viral diarrhea virus (BVDV) to construct strategy for the diagnostic tools and effective vaccine of BVD afterwards. A recombinant DNA clone (No. 29) was established successfully from cDNA for viral RNA tailed with adenine homopolymer at 3 -end. 32P-labeled DNA probes of 300~1, 800bp fragments, originating from the clone 29, directed specific DNA-RNA hybridization results with BVDV RNA. Recombinant DNA of the clone 29 was about 5,200bp representing 41.6% of the full length of Danish strain's RNA, and restriction sites were recognized for EooR I, Sst I, Hind III and Pst I restriction enzymes in the DNA fragment

  11. Recombinant baculovirus vectors expressing glutathione-S-transferase fusion proteins.

    Science.gov (United States)

    Davies, A H; Jowett, J B; Jones, I M

    1993-08-01

    Recombinant baculoviruses are a popular means of producing heterologous protein in eukaryotic cells. Purification of recombinant proteins away from the insect cell background can, however, remain an obstacle for many developments. Recently, prokaryotic fusion protein expression systems have been developed allowing single-step purification of the heterologous protein and specific proteolytic cleavage of the affinity tag moiety from the desired antigen. Here we report the introduction of these attributes to the baculovirus system. "Baculo-GEX" vectors enable baculovirus production of fusion proteins with the above advantages, but in a eukaryotic post-translational processing environment. Glutathione-S-transferase (GST) fusions are stable cytoplasmic proteins in insect cells and may therefore be released by sonication alone, avoiding the solubility problems and detergent requirements of bacterial systems. Thus large amounts of authentic antigen may be purified in a single, non-denaturing step. PMID:7763917

  12. Effective conductance method for the primordial recombination spectrum

    CERN Document Server

    Ali-Haïmoud, Yacine

    2012-01-01

    As atoms formed for the first time during primordial recombination, they emitted bound-bound and free-bound radiation leading to spectral distortions to the cosmic microwave background. These distortions might become observable in the future with high-sensitivity spectrometers, and provide a new window into physical conditions in the early universe. The standard multilevel atom method habitually used to compute the recombination spectrum is computationally expensive, impeding a detailed quantitative exploration of the information contained in spectral distortions thus far. In this work it is shown that the emissivity in optically thin allowed transitions can be factored into a computationally expensive but cosmology-independent part and a computationally cheap, cosmology-dependent part. The slow part of the computation consists in pre-computing temperature-dependent effective "conductances", linearly relating line or continuum intensity to departures from Saha equilibrium of the lowest-order excited states (2...

  13. Dissociative recombination in reactive flows related to planetary atmospheric entries

    Directory of Open Access Journals (Sweden)

    Bultel Arnaud

    2015-01-01

    Full Text Available The Dissociative Recombination (DR processes play a significant role in plasma chemistry. This article illustrates this role from the modeling point of view in the case of reactive flows related to atmospheric entry plasmas. Two situations are investigated, for which the studied plasma is nitrogen. The first configuration corresponds to the relaxation process behind a strong shock wave moving at high Mach number in a shock tube, the second one to the recombination taking place in an expanding plasma flowing in a diverging nozzle. In both cases, the collisional-radiative model CoRaM-N2, involving N2, N, N2+, N+ and electrons, is implemented in an Eulerian 1D code able to compute the aerodynamic fields; calculations are performed in standard conditions. We show that, according to the rate coefficients used for the DR processes, the population density of the charged species especially N2+ is strongly modified only for the post-shock flow.

  14. The 21-cm Signal from the cosmological epoch of recombination

    Energy Technology Data Exchange (ETDEWEB)

    Fialkov, A. [Departement de Physique, Ecole Normale Superieure, CNRS, 24 rue Lhomond, Paris, 75005 (France); Loeb, A., E-mail: anastasia.fialkov@phys.ens.fr, E-mail: aloeb@cfa.harvard.edu [Department of Astronomy, Harvard University, 60 Garden Street, MS-51, Cambridge, MA, 02138 (United States)

    2013-11-01

    The redshifted 21-cm emission by neutral hydrogen offers a unique tool for mapping structure formation in the early universe in three dimensions. Here we provide the first detailed calculation of the 21-cm emission signal during and after the epoch of hydrogen recombination in the redshift range of z ∼ 500–1,100, corresponding to observed wavelengths of 100–230 meters. The 21-cm line deviates from thermal equilibrium with the cosmic microwave background (CMB) due to the excess Lyα radiation from hydrogen and helium recombinations. The resulting 21-cm signal reaches a brightness temperature of a milli-Kelvin, orders of magnitude larger than previously estimated. Its detection by a future lunar or space-based observatory could improve dramatically the statistical constraints on the cosmological initial conditions compared to existing two-dimensional maps of the CMB anisotropies.

  15. Characterization of recombinant Raccoonpox Vaccine Vectors in Chickens

    Science.gov (United States)

    Hwa, S.-H.; Iams, K.P.; Hall, J.S.; Kingstad, B.A.; Osorio, J.E.

    2010-01-01

    Raccoonpox virus (RCN) has been used as a recombinant vector against several mammalian pathogens but has not been tested in birds. The replication of RCN in chick embryo fibroblasts (CEFs) and chickens was studied with the use of highly pathogenic avian influenza virus H5N1 hemagglutinin (HA) as a model antigen and luciferase (luc) as a reporter gene. Although RCN replicated to low levels in CEFs, it efficiently expressed recombinant proteins and, in vivo, elicited anti-HA immunoglobulin yolk (IgY) antibody responses comparable to inactivated influenza virus. Biophotonic in vivo imaging of 1-wk-old chicks with RCN-luc showed strong expression of the luc reporter gene lasting up to 3 days postinfection. These studies demonstrate the potential of RCN as a vaccine vector for avian influenza and other poultry pathogens. ?? American Association of Avian Pathologists 2010.

  16. Steady-state photoluminescent excitation characterization of semiconductor carrier recombination

    Science.gov (United States)

    Bhosale, J. S.; Moore, J. E.; Wang, X.; Bermel, P.; Lundstrom, M. S.

    2016-01-01

    Photoluminescence excitation spectroscopy is a contactless characterization technique that can provide valuable information about the surface and bulk recombination parameters of a semiconductor device, distinct from other sorts of photoluminescent measurements. For this technique, a temperature-tuned light emitting diode (LED) has several advantages over other light sources. The large radiation density offered by LEDs from near-infrared to ultraviolet region at a low cost enables efficient and fast photoluminescence measurements. A simple and inexpensive LED-based setup facilitates measurement of surface recombination velocity and bulk Shockley-Read-Hall lifetime, which are key parameters to assess device performance. Under the right conditions, this technique can also provide a contactless way to measure the external quantum efficiency of a solar cell.

  17. Fragmentation Functions for Heavy Baryons in the Recombination Model

    Institute of Scientific and Technical Information of China (English)

    彭茹

    2011-01-01

    Using the shower parton distributions determined by the recombination model, we predict the fragmentation functions for heavy baryons. Then we obtain the completed fragmentation functions of heavy quarks (c and b) splitting into their hadrons (mesons and baryons containing one heavy valence quark). The calculated process shows that the fragmentation functions for mesons and baryons are not independent if the hadronization of the shower partons is taken into account.%Using the shower parton distributions determined by the recombination model,we predict the fragmentation functions for heavy baryons.Then we obtain the completed fragmentation functions of heavy quarks(c and b)splitting into their hadrons(mesons and baryons containing one heavy valence quark).The calculated process shows that the fragmentation functions for mesons and baryons are not independent if the hadronization of the shower partons is taken into account.

  18. Electron-ion recombination study in argon at atmospheric pressure

    International Nuclear Information System (INIS)

    This study deals with a wall-stabilized arc burning in argon at atmospheric pressure. A transient mode is obtained using a fast thyristor connected to the electrodes, which short-circuits the discharge. By means of two wavelengths laser interferometry and spectroscopy measurements we have determined the temporal changes of the electron density, ground state atom density and excited atom density. We have shown that, when the electric field is suppressed, the electron temperature rapidly decreases to the gas temperature before changing electron and atom densities. This phenomenon is applied to determine the gas temperature and to evaluate the role played by ionization in electron density balance. The coefficients of ambipolar diffusion, ionization and recombination and an apparent recombination coefficient are determined versus electron temperature and compared with theoretical values

  19. Genetically Engineered Poxviruses for Recombinant Gene Expression, Vaccination, and Safety

    Science.gov (United States)

    Moss, Bernard

    1996-10-01

    Vaccinia virus, no longer required for immunization against smallpox, now serves as a unique vector for expressing genes within the cytoplasm of mammalian cells. As a research tool, recombinant vaccinia viruses are used to synthesize and analyze the structure--function relationships of proteins, determine the targets of humoral and cell-mediated immunity, and investigate the types of immune response needed for protection against specific infectious diseases and cancer. The vaccine potential of recombinant vaccinia virus has been realized in the form of an effective oral wild-life rabies vaccine, although no product for humans has been licensed. A genetically altered vaccinia virus that is unable to replicate in mammalian cells and produces diminished cytopathic effects retains the capacity for high-level gene expression and immunogenicity while promising exceptional safety for laboratory workers and potential vaccine recipients.

  20. Transgenic Expression of the Recombinant Phytase in Rice (Oryza sativa)

    Institute of Scientific and Technical Information of China (English)

    LIU Qiao-quan; LI Qian-feng; JIANG Li; ZHANG Da-jiang; WANG Hong-mei; GU Ming-hong; YAO Quan-hong

    2006-01-01

    In most of the cereal crop, phytic acid is the main storage form of phosphorus, which can decrease the bioavailability of phosphate. Transgenic expression of phytase is regarded as an efficient way to release phosphate from phytate in transgenic plants.In this study, a plant expression vector, containing the recombinant phytase gene driven by the maize ubiquitin (Ubi) promoter was constructed and introduced into an elite rice variety via Agrobacterium-mediated transformation. During the experiment, a total of 15 independent transgenic rice lines were regenerated. The results of PCR and Southern blot indicated that the target gene was integrated into the genome of transgenic rice plants. Moreover, the RT-PCR analysis of total RNAs extracted from the immature seeds of several transgenic lines showed that the recombinant phytase gene could be normally expressed. The inorganic phosphorus content, both in the mature seeds and the leaf was significantly higher in the transgenic plants than in the untransformed wild type.