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1.
Kimberlee K. Wallace Gregory F. Payne Marilyn K. Speedie 《Journal of industrial microbiology & biotechnology》1990,6(1):43-48
Summary A defined medium containing glucose and ammonium as the sole carbon and nitrogen sources was developed to support growth and streptonigrin production. In this defined medium, increased initial levels of ammonium resulted in increased growth suggesting that nitrogen is the growth limiting nutrient. In some cases, increased initial ammonium levels resulted in decreased specific streptonigrin productivity, suggesting that nitrogen regulatory mechanisms may adversely affect streptonigrin biosynthesis. This suggestion that nitrogen regulation adversely affects antibiotic biosynthesis is further supported by results from two studies in which the ammonium supply to the cells was controlled. In the first study, streptonigrin productivity and final titer were enhanced by the addition of an ammonium trapping agent. In the second experiment, when ammonium chloride was fed slowly throughout the course of cultivation, the production phase was lengthened and the maximum antibiotic concentration was enhanced compared to the batch controls containing either the same initial or the same total ammonium chloride levels. Although our results indicate streptonigrin production may be subject to nitrogen regulatory mechanisms, the effect of nitrogen on streptonigrin production cannot be strictly correlated to the extracellular ammonium concentration. In fact, we observed that when ammonium was depleted from the medium, streptonigrin production ceased. 相似文献
2.
Investigation of the role of the disulphide bond in the activity and structure of staphylococcal enterotoxin C1 总被引:13,自引:0,他引:13
Carolyn J. Hovde James C. Marr Marcy L. Hoffmann Sean P. Hackett Young-in Chi Kimberlee K. Crum Dennis L. Stevens Cynthia V. Stauffacher Gregory A. Bohach 《Molecular microbiology》1994,13(5):897-909
The goal of this study was to Investigate the role of the disulphide bond of staphylococcal enterotoxin C1 (SEC1) in the structure and activity of the toxin. Mutants unable to form a disulphide bond were generated by substituting alanine or serine for cysteine at positions 93 and/or 110. Although we did not directly investigate the residues between the disulphide linkage, tryptic lability showed that significant native structure in the cystine loop is preserved in the absence of covalent bonding between residues 93 and 110. Since no correlation was observed between the behaviour of these mutants with regard to toxin stability, emesis and T cell proliferation, we conclude that SEC1 -induced emesis and T cell proliferation are dependent on separate regions of the molecule. The disulphide bond itself is not an absolute requirement for either activity. However, conformation within or adjacent to the loop is important for emesis. Although mutants with alanine substitutions were not emetic, those with serine substitutions retained this activity, suggesting that the disulphide linkage stabilizes a crucial conformation but can be replaced by residues which hydrogen bond. 相似文献
3.
Steven A. Nadler Eugene T. Lyons Christopher Pagan Derek Hyman Edwin E. Lewis Kimberlee Beckmen Cameron M. Bell Aurelie Castinel Robert L. DeLong Padraig J. Duignan Cher Farinpour Kathy Burek Huntington Thijs Kuiken Diana Morgades Soraya Naem Richard Norman Corwin Parker Paul Ramos Terry R. Spraker Bárbara Berón-Vera 《International journal for parasitology》2013
Hookworms of the genus Uncinaria have been widely reported from juvenile pinnipeds, however investigations of their systematics has been limited, with only two species described, Uncinaria lucasi from northern fur seals (Callorhinus ursinus) and Uncinaria hamiltoni from South American sea lions (Otaria flavescens). Hookworms were sampled from these hosts and seven additional species including Steller sea lions (Eumetopias jubatus), California sea lions (Zalophus californianus), South American fur seals (Arctocephalus australis), Australian fur seals (Arctocephalus pusillus), New Zealand sea lions (Phocarctos hookeri), southern elephant seals (Mirounga leonina), and the Mediterranean monk seal (Monachus monachus). One hundred and thirteen individual hookworms, including an outgroup species, were sequenced for four genes representing two loci (nuclear ribosomal DNA and mitochondrial DNA). Phylogenetic analyses of these sequences recovered seven independent evolutionary lineages or species, including the described species and five undescribed species. The molecular evidence shows that U. lucasi parasitises both C. ursinus and E. jubatus, whereas U. hamiltoni parasitises O. flavescens and A. australis. The five undescribed hookworm species were each associated with single host species (Z. californianus, A. pusillus, P. hookeri, M. leonina and M. monachus). For parasites of otarids, patterns of Uncinaria host-sharing and phylogenetic relationships had a strong biogeographic component with separate clades of parasites from northern versus southern hemisphere hosts. Comparison of phylogenies for these hookworms and their hosts suggests that the association of U. lucasi with northern fur seals results from a host-switch from Steller sea lions. Morphometric data for U. lucasi shows marked host-associated size differences for both sexes, with U. lucasi individuals from E. jubatus significantly larger. This result suggests that adult growth of U. lucasi is reduced within the host species representing the more recent host–parasite association. Intraspecific host-induced size differences are inconsistent with the exclusive use of morphometrics to delimit and diagnose species of Uncinaria from pinnipeds. 相似文献
4.
Ronan A. Lyons Denise Kendrick Elizabeth M. L. Towner Carol Coupland Mike Hayes Nicola Christie Judith Sleney Sarah Jones Richard Kimberlee Sarah E. Rodgers Samantha Turner Mariana Brussoni Yana Vinogradova Tinnu Sarvotham Steven Macey 《PloS one》2013,8(4)
Objective
To determine whether advocacy targeted at local politicians leads to action to reduce the risk of pedestrian injury in deprived areas.Design
Cluster randomised controlled trial.Setting
239 electoral wards in 57 local authorities in England and Wales.Participants
617 elected local politicians.Interventions
Intervention group politicians were provided with tailored information packs, including maps of casualty sites, numbers injured and a synopsis of effective interventions.Main outcome measures
25–30 months post intervention, primary outcomes included: electoral ward level: percentage of road traffic calmed; proportion with new interventions; school level: percentage with 20 mph zones, Safe Routes to School, pedestrian training or road safety education; politician level: percentage lobbying for safety measures. Secondary outcomes included politicians’ interest and involvement in injury prevention, and facilitators and barriers to implementation.Results
Primary outcomes did not significantly differ: % difference in traffic calming (0.07, 95%CI: −0.07 to 0.20); proportion of schools with 20 mph zones (RR 1.47, 95%CI: 0.93 to 2.32), Safe Routes to School (RR 1.34, 95%CI: 0.83 to 2.17), pedestrian training (RR 1.23, 95%CI: 0.95 to 1.61) or other safety education (RR 1.16, 95%CI: 0.97 to 1.39). Intervention group politicians reported greater interest in child injury prevention (RR 1.09, 95%CI 1.03 to 1.16), belief in potential to help prevent injuries (RR 1.36, 95%CI 1.16 to 1.61), particularly pedestrian safety (RR 1.55, 95%CI 1.19 to 2.03). 63% of intervention politicians reported supporting new pedestrian safety schemes. The majority found the advocacy information surprising, interesting, effectively presented, and could identify suitable local interventions.Conclusions
This study demonstrates the feasibility of an innovative approach to translational public health by targeting local politicians in a randomised controlled trial. The intervention package was positively viewed and raised interest but changes in interventions were not statistically significance. Longer term supported advocacy may be needed.Trial Registration
Current Controlled Trials ISRCTN91381117 相似文献5.
Tschan MP Fischer KM Fung VS Pirnia F Borner MM Fey MF Tobler A Torbett BE 《The Journal of biological chemistry》2003,278(44):42750-42760
6.
Rady PL Surendran S Vu AT Hawkins JC Michals-Matalon K Tyring SK Merren J Kumar AK Matalon R 《Genetic testing》2002,6(3):211-215
Sanfilippo A syndrome is an autosomal recessive lysosomal storage disease. This disease was reported in the Cayman Islands population with carrier frequency of 1/7 to 1/10 in the West Bay district of Grand Cayman. The carrier testing of Sanfilippo A disease for families at risk was carried out using the thermal characteristics of sulfamidase activity. In the present study, a search for mutations in the sulfamidase gene in an index family was performed. In addition, 77 individuals, relatives of children with Sanfilippo A syndrome, were also studied by single-strand conformation polymorphism (SSCP), restriction fragment-length polymorphism (RFLP) analyses, and sequencing. A single mutation, G746A (R245H), was found in the family, with the patient being homozygous and both parents and 1 of the 3 siblings being carriers. Among the 77 family members of the patient with Sanfilippo syndrome, the same mutation was found among carriers of the disease. The finding of a single mutation supports the idea of a founder effect, which facilitates accurate carrier identification of Sanfilippo A syndrome in the population of Cayman Islands. 相似文献
7.
Tree species effects on ecosystem water-use efficiency in a high-elevation, subalpine forest 总被引:1,自引:0,他引:1
Russell K. Monson Margaret R. Prater Jia Hu Sean P. Burns Jed P. Sparks Kimberlee L. Sparks Laura E. Scott-Denton 《Oecologia》2010,162(2):491-504
Ecosystem water-use efficiency (eWUE; the ratio of net ecosystem productivity to evapotranspiration rate) is a complex landscape-scale
parameter controlled by both physical and biological processes occurring in soil and plants. Leaf WUE (lWUE; the ratio of
leaf CO2 assimilation rate to transpiration rate) is controlled at short time scales principally by leaf stomatal dynamics and this
control varies among plant species. Little is known about how leaf-scale variation in lWUE influences landscape-scale variation
in eWUE. We analyzed approximately seven thousand 30-min averaged eddy covariance observations distributed across 9 years
in order to assess eWUE in two neighboring forest communities. Mean eWUE was 19% lower for the community in which Engelmann
spruce and subalpine fir were dominant, compared to the community in which lodgepole pine was dominant. Of that 19% difference,
8% was attributed to residual bias in the analysis that favored periods with slightly drier winds for the spruce-fir community.
In an effort to explain the remaining 11% difference, we assessed patterns in lWUE using C isotope ratios. When we focused
on bulk tissue from older needles we detected significant differences in lWUE among tree species and between upper and lower
canopy needles. However, when these differences were scaled to reflect vertical and horizontal leaf area distributions within
the two communities, they provided no power to explain differences in eWUE that we observed in the eddy covariance data. When
we focused only on bulk needle tissue of current-year needles for 3 of the 9 years, we also observed differences in lWUE among
species and in needles from upper and lower parts of the canopy. When these differences in lWUE were scaled to reflect leaf
area distributions within the two communities, we were able to explain 6.3% of the differences in eWUE in 1 year (2006), but
there was no power to explain differences in the other 2 years (2003 and 2007). When we examined sugars extracted from needles
at 3 different times during the growing season of 2007, we could explain 3.8–6.0% of the differences in eWUE between the two
communities, but the difference in eWUE obtained from the eddy covariance record, and averaged over the growing season for
this single year, was 32%. Thus, overall, after accounting for species effects on lWUE, we could explain little of the difference
in eWUE between the two forest communities observed in the eddy covariance record. It is likely that water and C fluxes from
soil, understory plants, and non-needle tissues, account for most of the differences observed in the eddy covariance data.
For those cases where we could explain some of the difference in eWUE on the basis of species effects, we partitioned the
scaled patterns in lWUE into two components: a component that is independent of canopy leaf area distribution, and therefore
only dependent on species-specific differences in needle physiology; and a component that is independent of species differences
in needle physiology, and only dependent on species-specific influences on canopy leaf area distribution. Only the component
that is dependent on species influences on canopy leaf area distribution, and independent of inherent species differences
in needle physiology, had potential to explain differences in eWUE between the two communities. Thus, when tree species effects
are important, canopy structure, rather than species-specific needle physiology, has more potential to explain patterns in
eWUE. 相似文献
8.
9.
Muraski JA Rota M Misao Y Fransioli J Cottage C Gude N Esposito G Delucchi F Arcarese M Alvarez R Siddiqi S Emmanuel GN Wu W Fischer K Martindale JJ Glembotski CC Leri A Kajstura J Magnuson N Berns A Beretta RM Houser SR Schaefer EM Anversa P Sussman MA 《Nature medicine》2007,13(12):1467-1475
The serine-threonine kinases Pim-1 and Akt regulate cellular proliferation and survival. Although Akt is known to be a crucial signaling protein in the myocardium, the role of Pim-1 has been overlooked. Pim-1 expression in the myocardium of mice decreased during postnatal development, re-emerged after acute pathological injury in mice and was increased in failing hearts of both mice and humans. Cardioprotective stimuli associated with Akt activation induced Pim-1 expression, but compensatory increases in Akt abundance and phosphorylation after pathological injury by infarction or pressure overload did not protect the myocardium in Pim-1-deficient mice. Transgenic expression of Pim-1 in the myocardium protected mice from infarction injury, and Pim-1 expression inhibited cardiomyocyte apoptosis with concomitant increases in Bcl-2 and Bcl-X(L) protein levels, as well as in Bad phosphorylation levels. Relative to nontransgenic controls, calcium dynamics were significantly enhanced in Pim-1-overexpressing transgenic hearts, associated with increased expression of SERCA2a, and were depressed in Pim-1-deficient hearts. Collectively, these data suggest that Pim-1 is a crucial facet of cardioprotection downstream of Akt. 相似文献
10.
Wang L Surendran S Michals-Matalon K Bhatia G Tanskley S Koch R Grady J Tyring SK Stevens RC Guttler F Matalon R 《Genetic testing》2007,11(2):174-178
Tetrahydrobiopterin (BH4) is a co-factor that enhances the activity of other enzymes, and this co-factor level is found to be affected in phenylketonuria (PKU), an amino acid metabolism disorder. The present study was aimed at understanding the effect of BH4 on mutations in the regulatory domain of phenylalanine hydroxylase (PAH). Among 14 patients, 5 patients were classical PKU, 3 were atypical PKU, and 6 were mild PKU. All of these patients had at least one mutation in the regulatory domain. Patients were given 10 mg/kg BH4, and the response of blood phenylalanine (Phe) levels was monitored following treatment. The level of blood Phe decreased after BH4 treatment in all of the patients. These studies suggest that mutations in the regulatory domain also responded to BH4 even if the patient had classical PKU. 相似文献