bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absence of the major light-harvesting antenna proteins alters the redox properties of photosystem II reaction centres in thechlorina F2mutant of barley
Authors: Krol Marianna , Ivanov Alexander G. , Booij-James Isabelle , Mattoo Autar K. , Sane P. V. , Hüner Norman P.A. 
Published: September 2009

Although the chlorina F2 mutant of barley specifically exhibits reduced levels of the major light-harvesting polypeptides associated with photosystem II (PSII), thermoluminescence measurements of photosystem reaction centre photochemistry revealed that S2/S3QB–charge recombinations were shifted to lower temperatures, while the characteristic peak of S2QA–charge recombinations was shifted to higher temperatures compared with wild-type (WT) barley. Thus, we show that the absence of the major light-harvesting polypeptides affects the redox properties of PSII reaction centres. Radiolabeling studies in vivo and in vitro with [32P]orthophosphate or [γ-32P]ATP, respectively, demonstrated that the D1 PSII reaction centre polypeptide is phosphorylated in both the WT and the F2 mutant. In contrast with the radiolabeling results, phosphorylation of D1 and other PSII proteins, although detected in WT barley, was ambiguous in the F2 mutant when the phosphothreonine antibody method of detection was used. Thus, caution must be exercised in the use of commercially available phosphothreonine antibodies to estimate thylakoid polypeptide phosphorylation. Furthermore, in membrano, the D1 polypeptide of the F2 mutant was less susceptible to trypsin treatment than that of WT barley. The role of the light-harvesting complex in modulating the structure and function of the D1 polypeptide of PSII reaction centers is discussed.
Interaction of tRNA with antitumor polyamine analogues
Authors: N’soukpoé-Kossi C. N. , Ahmed Ouameur A. , Thomas T. , Thomas T. J. , Tajmir-Riahi H. A. 
Published: September 2009

We studied the interaction between tRNA and three polyamine analogues (1,11-diamino-4,8-diazaundecane·4HCl (333), 3,7,11,15-tetrazaheptadecane·4HCl (BE-333), and 3,7,11,15,19-pentazahenicosane·5HCl (BE-3333)) using FTIR, UV-visible, and CD spectroscopic methods. Spectroscopic evidence showed that polyamine analogues bound tRNA via guanine N7, adenine, uracil O2, and the backbone phosphate (PO2–) groups, while the most reactive sites for biogenic polyamines were guanine N7/O6, adenine N7, uracil O2, and sugar 2′-OH groups as well as the backbone phosphate group. The binding constants of polyamine analogue – tRNA recognition were lower than those of the biogenic polyamine – tRNA complexes, with K333= 2.8 (±0.5) × 104, KBE-333= 3.7 (±0.7) × 104, KBE-3333= 4.0 (±0.9) × 104, Kspm= 8.7 (±0.9) × 105, Kspd= 6.1 (±0.7) × 105, and Kput= 1.0 (±0.3) × 105mol/L. tRNA remained in the A-family conformation; however, it aggregated at high polyamine analogue concentrations.
Probing Alzheimer amyloid peptide aggregation using a cell-free fluorescent protein refolding method
Authors: Arslan Pharhad Eli , Chakrabartty Avijit 
Published: September 2009

Fibrillation of the Alzheimer β-amyloid peptide (Aβ) and (or) formation of toxic oligomers are key pathological events in Alzheimer’s disease. Several strategies have been introduced to identify small molecule aggregation inhibitors, and based on these methods, a number of aggregation inhibitors have been identified. However, most of these methods use chemically synthesized Aβ42 peptides, which are difficult to maintain in a monomeric state at neutral pH where anti-aggregation screening is usually carried out. We have developed a cell-free Aβ42 aggregation assay based on fluorescence protein refolding. This assay utilizes nanomolar concentrations of protein. We genetically fused Aβ42 to the N-terminus of vYFP, a variant of of GFP, and expressed and purified the folded fusion protein. The refolding efficiency of Aβ42–vYFP fusion was inversely correlated with the solubility of Aβ42. Using fluorescence to monitor refolding of Aβ42–vYFP, we confirmed that Zn2+binds to Aβ42 and increases its aggregation. The IC50value estimated for Zn binding is 3.03 ± 0.65 µmol/L. We also show that this technique is capable of monitoring the aggregation of chemically synthesized Aβ42.
Exendin-4 exerts its effects through the NGF/p75NTRsystem in diabetic mouse pancreas
Authors: Gezginci-Oktayoglu Selda , Bolkent Sehnaz 
Published: September 2009

Glucagon-like peptide-1 (GLP-1) ameliorates the symptoms of diabetes through stimulation of insulin secretion. We have investigated the possible components of cellular mechanism triggered by exendin-4, a potent GLP-1 receptor agonist, in streptozotocin (STZ) induced diabetic mice pancreas. BALB/c male mice were divided into four groups for this investigation. The first group was given citrate buffer only, the second group was administered exendin-4 alone, the third group received STZ, and the fourth group was given both STZ and exendin-4. Exendin-4 (3 µg/kg) was administered by daily subcutaneous injection for 30 days after the animals were rendered diabetic by administration of STZ (200 mg/kg). With exendin-4 treatment on diabetic mice, the following results were noted: (i) exendin-4 suppressed the increase in plasma glucose and inhibited somatostatin expression induced by STZ, (ii) reduction of insulin prevalence was inhibited, while expression of p75 neurotrophin receptor (p75NTR), pancreatic nerve growth factor (NGF), and NGF-positive islet cell prevalence increased, (iii) there were no alterations in the severity of proliferated cell nuclear antigen positive or apoptotic beta cells in pancreatic islets, and (iv) pancreatic catalase, glutathione peroxidase, and superoxide dismutase activities significantly increased. In conclusion, these data suggest that exendin-4 might exert its actions through the NGF/p75NTRsystem and decrease somatostatin expression.
Molecular characterization of the pL40 protein inLeptospira interrogans
Authors: Zhao Wei , Chen Chun-Yan , Zhang Xiang-Yan , Lai Wei-Qiang , Hu Bao-Yu , Zhao Guo-Ping , Qin Jin-Hong , Guo Xiao-Kui 
Published: September 2009

Leptospirosis is a widespread zoonotic disease caused by pathogenic leptospires. The identification of outer membrane proteins (OMPs) conserved among pathogenic leptospires, which are exposed on the leptospiral surface and expressed during mammalian infection, has become a major focus of leptospirosis research. pL40, a 40 kDa protein coded by the LA3744 gene in Leptospira interrogans , was found to be unique to Leptospira . Triton X-114 fractionation and flow cytometry analyses indicate that pL40 is a component of the leptospiral outer membrane. The conservation of pL40 among Leptospira strains prevalent in China was confirmed by both Western blotting and PCR screening. Furthermore, the pL40 antigen could be recognized by sera from guinea pigs and mice infected with low-passage L. interrogans. These findings indicate that pL40 may serve as a useful serodiagnostic antigen and vaccine candidate for L. interrogans.
Characterization of tetracycline- and ampicillin-resistant Escherichia coli isolated from the feces of feedlot cattle over the feeding period
Authors: Mirzaagha Parasto , Louie Marie , Read Ron R. , Sharma Ranjana , Yanke L. Jay , Topp Edward , McAllister Tim A. 
Published: September 2009

The objective of this study was to investigate tetracycline and ampicillin resistance in Escherichia coli isolated from the feces of 50 crossbred steers housed in 5 feedlot pens. The steers were not administered antibiotics over a 246-day feeding period. A total of 216 isolates were selected for further characterization. The E. coli isolates were selected on MacConkey agar or on MacConkey agar amended with ampicillin (50 µg/mL) or tetracycline (4 µg/mL). Pulsed-field gel electrophoresis (PFGE) typing (XbaI digestion), screening against 11 antibiotics, and multiplex PCR for 14 tet and 3 β-lactamase genes were conducted. Prevalence of antimicrobial resistance in E. coli at each sampling day was related both temporally and by pen. Multiplex PCR revealed that tet(B) was most prevalent among tetracycline-resistant isolates, whereas β-lactamase tem1-like was detected mainly in ampicillin-resistant isolates. Our results suggest that antimicrobial resistance in E. coli populations persists over the duration of the feeding period, even in the absence of in-feed antibiotics. Many of the isolates with the same antibiograms had indistinguishable PFGE patterns. Characterization of the factors that influence the nature of this nonselective resistance could provide important information for consideration in the regulation of in-feed antimicrobials for feedlot cattle.
Disruption of the 2-methylcitric acid cycle and evaluation of poly-3-hydroxybutyrate-co-3-hydroxyvalerate biosynthesis suggest alternate catabolic pathways of propionate inBurkholderia sacchari
Authors: Pereira Erica Mendes , Silva-Queiroz Sonia Regina , Cabrera Gomez José Gregório , Silva Luiziana Ferreira 
Published: September 2009

The objective of the present work was to evaluate the relevance of the 2-methylcitric acid cycle (2MCC) to the catabolism of propionate in Burkholderia sacchari . Two B. sacchari mutants unable to grow on propionate were obtained: one disrupted in acnM, and the other in acnM and prpC deleted. An operative 2MCC significantly reduces the bacterial ability to incorporate 3-hydroxyvalerate (3HV) into a biodegradable copolyester accumulated from carbohydrates plus propionate. The efficiency of the mutants in converting propionate to 3HV units (Y3HV/prp) increased from 0.09 g·g–1to 0.81–0.96 g·g–1, indicating that acnM and prpC are both essential for growth on propionate. None of the mutations resulted in achievement of the maximum theoretical Y3HV/prp(1.35 g·g–1). When increasing concentrations of propionate were supplied, decreasing values of Y3HV/prpwere observed. The results obtained corroborate the hypothesis of the presence of other propionate catabolic pathways in B. sacchari. The 2MCC would be the more operative pathway, but a second pathway, which remains to be elucidated, would assume more importance under propionate concentrations of 1 g·L–1or higher. The efficiency in converting propionate to 3HV units can be improved by decreasing the propionate concentrations, owing to the role of the 2MCC.
Altitudinal distribution of microfungi associated withBetula ermaniileaf litter on Mt. Rishiri, northern Japan
Authors: Osono Takashi , Hirose Dai 
Published: September 2009

The altitudinal distribution of microfungi associated with Betula ermanii Cham. leaf litter was investigated on Mt. Rishiri (1719 m), northern Japan. Fallen leaves were collected at five sites of different altitudes (appoximately 300, 600, 900, 1200, and 1500 m above sea level) along a transect on the northern slope of Mt. Rishiri. A total of 35 species were isolated from Betula leaf litter of which 12 occurred frequently and were regarded as dominant microfungi. Species richness, diversity, and equitability of microfungal assemblages were lower at Site 1500 than at the other sites. Similarities in species composition were relatively high among Sites 300, 600, and 900, but similarities between these sites and sites at the higher altitudes (i.e., Sites 1200 and 1500) were relatively low. Similarity of species composition was relatively low between Sites 1200 and 1500. Cluster analysis showed that the 12 major microfungal species were classified into four groups according to their pattern of altitudinal distribution that peaked at Sites 600, 900, 1200, and 1500, respectively. These results suggest that the diversity and species composition of Betula microfungi are sensitive to environmental changes along the altitudinal transect on Mt. Rishiri, and this is especially so at the altitudes higher than approximately 1200 m. This implies that future environmental changes will have impacts on mountainous ecosystems through the changes in diversity and functional aspects of microfungal assemblages.
Influence of arbuscular mycorrhizae on the root system of maize plants under salt stress
Authors: Sheng Min , Tang Ming , Chen Hui , Yang Baowei , Zhang Fengfeng , Huang Yanhui 
Published: September 2009

Salt stress has become a severe global problem, and salinity is one of the most important abiotic factors limiting plant growth and yield. It is known that arbuscular mycorrhizal (AM) fungi decrease plant yield losses under salinity. With the aim of determining whether AM inoculation would give an advantage to root development under salt stress, a greenhouse experiment was carried out with AM or without AM fungi. Maize plants were grown in a sand and soil mixture with 5 NaCl levels (0, 0.5, 1.0, 1.5, and 2.0 g/kg dry substrate) for 55 days, following 15 days of nonsaline pretreatment. At all salt levels, mycorrhizal plants had higher dry shoot and root mass, higher root activity, and lower root to shoot ratios than non-mycorrhizal plants. In salt-free soil, root length, root surface area, root volume, and number of root tips and forks were significantly larger in mycorrhizal plants than in non-mycorrhizal plants, whereas, under salt stress, average root diameter and root volume of mycorrhizal plants were larger than those of non-mycorrhizal plants. Regardless of the NaCl level, mycorrhizal plants had lower specific root length, lower percentage of root length in the 0–0.2 mm diameter class, and higher percentage of root length in both the 0.2–0.4 mm and 0.4–0.6 mm diameter classes, which suggests that the root system shows a significant shift towards a thicker root system when maize plants were inoculated with Glomus mosseae (Nicolson & Gerdemann). The results presented here indicate that the improvements in root activity and the coarse root system of mycorrhizal maize may help in alleviating salt stress on the plant.
Comparison of media used to evaluateRhizobium leguminosarumbivarviciaefor phosphate-solubilizing ability
Authors: Xie Jia , Knight J. Diane , Leggett Mary E. 
Published: September 2009

Rhizobium leguminosarum is well known for its ability to fix nitrogen (N). In addition, its capacity to solubilize phosphate (Ph) has been receiving attention in recent years. Our ultimate objective was to select a R. leguminosarum bv. viciae isolate with superior Ph-solubilizing ability. The first step was to identify a culture medium that is sensitive and effective in identifying the ability of R. leguminosarum bv. viciae isolates to solubilize Ph. Thirty isolates were evaluated for Ph solubilization in broth and on solid formulations of three media: yeast mannitol extract (YEM), National Botanical Research Institute phosphate nutrient medium (MNBRI), and Pikovskaya phosphate medium (PVK). All media contained 5 g/L CaHPO4as the only phosphorus (P) source. All 30 isolates increased the Ph concentration in liquid cultures, but the amount of Ph released into solution by individual isolates varied from one medium to another. In contrast, only a subset of the 30 isolates solubilized Ph on the solid cultures. Furthermore, some of the isolates that were able to solubilize Ph were only able to do so on a single medium. Regression analysis revealed no relationship between the Ph concentration in the liquid media and the zones of clearing on the solid media (p > 0.05). Although the pH of all of the liquid media dropped after 12 days of growth of the isolates, a relationship between Ph concentration and pH existed only for the MNBRI medium (r2= 0.485, p < 0.001). Increasing the amount of N in the MNBRI medium from 0.1 g/L of (NH4)2SO4to 0.5 g/L of (NH4)2SO4did not affect the amount of Ph in solution, but it profoundly reduced the survival of the R. leguminosarum by approximately 50-fold. Consequently, the surviving bacteria were either more efficient at solubilizing Ph in the high N media or organic acids released from the lysis of the dead cells solubilized the CaHPO4source.
Sex and hormonal influences on the nicotine-induced attenuation of isoprenaline vasodilations in the perfused rat kidney
Authors: El-Mas Mahmoud M. , El-Gowilly Sahar M. , Gohar Eman Y. , Ghazal Abdel-Rheem M. 
Published: September 2009

We previously reported that nicotine impairs β-adrenoceptor-mediated renovascular control in male rats. Here, we investigated the roles of sex and estrogen in nicotine–β-adrenoceptor renal interaction. The effect of nicotine on renal vasodilations caused by isoprenaline was evaluated in phenylephrine-preconstricted perfused kidneys of male and proestrus female rats in absence and presence of NG-nitro-l-arginine (l-NNA, a NOS inhibitor). The interaction was also studied in diestrus and ovariectomized (OVX) rats treated with or without estradiol, tamoxifen, or l-arginine. Bolus isoprenaline (0.03–8.0 µmol) elicited dose-dependent renal vasodilations; female preparations were more sensitive (smaller ED50) to isoprenaline-induced vasodilation than were male preparations. Infusion of nicotine (500 µmol/L) reduced isoprenaline vasodilations in the 2 sexes and abolished male-female differences in isoprenaline responses. l-NNA reduced isoprenaline vasodilations in proestrus but not in male preparations. Also, in the presence of l-NNA, nicotine caused no attenuation of isoprenaline vasodilations in proestrus preparations. Renal responses to isoprenaline together with the attenuation of these responses by nicotine were reduced by OVX and restored to near-proestrus levels after supplementation with estradiol, the estrogen receptor modulator tamoxifen, or l-arginine. In diestrus rats, which exhibited reduced plasma estradiol, nicotine caused less attenuation of isoprenaline vasodilations. We conclude that impairment of estrogen–NOS signaling constitutes a possible cellular mechanism for the detrimental effect of nicotine on isoprenaline vasodilations in female rats. The mechanism of the nicotine-induced attenuation of isoprenaline vasodilation in male kidneys, which is NOS-independent, remains to be elucidated.
Rosiglitazone inhibits high glucose-induced apoptosis in human umbilical vein endothelial cells through the PI3K/Akt/eNOS pathway
Authors: Wu Jing , Lei Min-Xiang , Xie Xiao-Yun , Liu Lan , She Yan-Mei , Mo Juan , Wang Shan 
Published: September 2009

Previous studies have shown that the phosphatidylinositol 3-kinase / Akt / endothelial nitric oxide synthase / NO (PI3K/Akt/eNOS/NO) pathway is involved in high glucose-induced endothelial cell apoptosis and rosiglitazone has a protective effect on endothelium. In the present study, we investigated the antiapoptotic effect of rosiglitazone on human umbilical vein endothelial cells (HUVECs) exposed to high glucose and explored its possible mechanism. Treatment of high glucose (33 mmol/L) for 48 h significantly induced the apoptosis of HUVECs, concomitantly with increased caspase-3 activity. High glucose treatment also decreased Akt and eNOS phosphorylation levels with subsequent NO production. All these alterations induced by high glucose were attenuated by rosiglitazone (1 µmol/L). Interestingly, the antiapoptotic effect of rosiglitazone was inhibited by PI3K inhibitor (LY294002, wortmannin) or eNOS inhibitor NG-l-nitro-arginine methyl ester (l-NAME). The reverse effects of rosiglitazone on phosphorylation of Akt and eNOS with subsequent NO production were also inhibited by LY294002, wortmannin or l-NAME, respectively. These findings suggest that rosiglitazone inhibits high glucose-induced apoptosis in HUVECs through the PI3K/Akt/eNOS pathway.
Parasitism, mercury contamination, and stable isotopes in fish-eating double-crested cormorants: no support for the co-ingestion hypothesis
Authors: Robinson S. A. , Forbes M. R. , Hebert C. E. 
Published: September 2009

Mercury and parasitism have been positively correlated in free-ranging birds. One proposed explanation is that mercury reduces host immunity, resulting in a greater susceptibility to parasitism. However, alternative explanations should be addressed to further inform and test hypotheses about relationships between mercury and parasitism. We investigated whether total mercury and Contracaecum spp. were correlated in double-crested cormorants ( Phalacrocorax auritus (Lesson, 1831)) and whether there was support for mercury and infective stages of parasites being co-ingested. For breeding cormorants, males had 1.5 times more total mercury in breast muscle than did females and >2 times more Contracaecum spp. in the proventriculus and stomach region. Males responsible for the sex biases in mercury concentration were not the same males responsible for sex biases in parasitism, hence separate explanations for these patterns were required. Males foraged in more pelagic areas and at a slightly lower trophic level than did females, as determined by stable C and N isotope signatures, respectively. These sex differences in foraging and expected differential consumption of intermediate fish hosts could explain the sex bias in parasitism but not the sex bias in mercury concentration. We suggest when testing contaminant–parasite linkages that sex differences in exposure be addressed.
Safety of Binodenoson, a Selective Adenosine A2AReceptor Agonist Vasodilator Pharmacological Stress Agent, in Healthy Subjects With Mild Intermittent Asthma
Authors: Murray John J. , Weiler John M. , Schwartz Lawrence B. , Busse William W. , Katial Rohit K. , Lockey Richard F. , McFadden E.R. , Pixton Glenn C. , Barrett Richard J. 
Published: September 2009

Background—The pharmacological stress agents adenosine and dipyridamole are contraindicated in asthma patients because of the risk of adenosine receptor-mediated bronchospasm. Binodenoson, a selective adenosine A2Areceptor agonist, produces maximal coronary hyperemia during pharmacological stress testing yet has a low affinity for the adenosine A1, A2B, and A3receptors that are probably responsible for bronchospasm. This study was conducted to assess the safety of binodenoson in 87 healthy young adult volunteers with documented mild, intermittent asthma.Methods and Results—This study consisted of a dose-escalating, single-blinded phase and a placebo-controlled, double-blinded phase conducted in healthy, young adults with documented mild, intermittent, asthma. In the single-blinded phase, 3 sequential cohorts of 8 subjects received intravenous binodenoson (0.5, 1.0, and 1.5 μg/kg). In the double-blinded phase, commenced after medical review of results from the single-blinded phase, subjects were randomly assigned 2:1 to either binodenoson 1.5 μg/kg (n=41) or placebo (n=22). The primary end point was clinically significant bronchoconstriction, defined as a decrease in forced expiratory volume in 1 second of ≥20% from the preinjection measure. Secondary safety end points were changes from preinjection measure in forced expiratory volume in 1 second, forced vital capacity, and forced expiratory flow during the middle 50% of the forced vital capacity; vital signs; pulse oximetry; and adverse events. Binodenoson caused no clinically significant bronchoconstriction or alterations in pulmonary function parameters and transiently increased heart rate and systolic blood pressure. The most common treatment-emergent adverse events were tachycardia, dizziness, and flushing.Conclusions—Binodenoson was safe, well tolerated, and caused no clinically significant bronchoconstriction or pulmonary responses in a small population of healthy subjects with mild, intermittent asthma.