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41.
Phytoene synthase catalyzes the dimerization of two molecules of geranylgeranyl pyrophosphate to phytoene and has been shown to be rate limiting for the synthesis of carotenoids. To elucidate if the capacity to produce phytoene is limiting also in the seed of Arabidopsis (Wassilewskija), a gene coding for an endogenous phytoene synthase was cloned and coupled to a seed-specific promoter, and the effects of the overexpression were examined. The resulting transgenic plants produced darker seeds, and extracts from the seed of five overexpressing plants had a 43-fold average increase of beta-carotene and a total average amount of beta-carotene of approximately 260 microg g-1 fresh weight. Lutein, violaxanthin, and chlorophyll were significantly increased, whereas the levels of zeaxanthin only increased by a factor 1.1. In addition, substantial levels of lycopene and alpha-carotene were produced in the seeds, whereas only trace amounts were found in the control plants. Seeds from the transgenic plants exhibited delayed germination, and the degree of delay was positively correlated with the increased levels of carotenoids. The abscisic acid levels followed the increase of the carotenoids, and plants having the highest carotenoid levels also had the highest abscisic acid content. Addition of gibberellic acid to the growth medium only partly restored germination of the transgenic seeds. 相似文献
42.
Lindgren N Xu ZQ Lindskog M Herrera-Marschitz M Goiny M Haycock J Goldstein M Hökfelt T Fisone G 《Journal of neurochemistry》2000,74(6):2470-2477
The activity of tyrosine hydroxylase, the rate-limiting enzyme in the biosynthesis of dopamine, is stimulated by phosphorylation. In this study, we examined the effects of activation of NMDA receptors on the state of phosphorylation and activity of tyrosine hydroxylase in rat striatal slices. NMDA produced a time-and concentration-dependent increase in the levels of phospho-Ser(19)-tyrosine hydroxylase in nigrostriatal nerve terminals. This increase was not associated with any changes in the basal activity of tyrosine hydroxylase, measured as DOPA accumulation. Forskolin, an activator of adenylyl cyclase, stimulated tyrosine hydroxylase phosphorylation at Ser(40) and caused a significant increase in DOPA accumulation. NMDA reduced forskolin-mediated increases in both Ser(40) phosphorylation and DOPA accumulation. In addition, NMDA reduced the increase in phospho-Ser(40)-tyrosine hydroxylase produced by okadaic acid, an inhibitor of protein phosphatase 1 and 2A, but not by a cyclic AMP analogue, 8-bromo-cyclic AMP. These results indicate that, in the striatum, glutamate decreases tyrosine hydroxylase phosphorylation at Ser(40) via activation of NMDA receptors by reducing cyclic AMP production. They also provide a mechanism for the demonstrated ability of NMDA to decrease tyrosine hydroxylase activity and dopamine synthesis. 相似文献
43.
The impact of length-variable data and alignment criterion on the phylogeny of Decapodiformes (Mollusca: Cephalopoda) 总被引:1,自引:0,他引:1
Annie R. Lindgren Marymegan Daly 《Cladistics : the international journal of the Willi Hennig Society》2007,23(5):464-476
In molecular phylogenetics, mode of analysis is typically the primary reason cited for obtaining different topologies. However, sequence alignment is as important in determining topology as analytical method or optimality criterion, particularly for length-variable sequences. We investigate the effect of alignment strategy and parameters in an analysis of length-variable 18S rDNA sequences from 41 oceanic squids (Decapodiformes), focusing particularly on the impact of including variable regions on the resulting topology. Decapodiformes are an enigmatic group of molluscs whose evolutionary relationships remain unclear because standard molecular analyses have continued to produce poorly supported or poorly resolved trees, possibly due to elevated levels of molecular evolution. We find that alignment strategy (Clustal X versus POY) has a greater affect on topology than does parameter choice. Some groups were robust to shifts in methodology, including cuttlefishes (Sepiidae), bobtail squids (Sepiolidae) and pygmy squids (Idiosepiidae). No alignment strategy supported the monophyly of Oegopsida, although Myopsida did consistently form a monophyletic group. The variable regions consistently provided more well-supported and well-resolved trees than the conserved regions alone, indicating the phylogenetic importance of including length-variable data. © The Willi Hennig Society 2007. 相似文献
44.
Gunilla Journath Niklas Hammar Stig Elofsson Anette Linnersj? Max Vikstr?m G?ran Walldius Ingvar Krakau Peter Lindgren Ulf de Faire Mai-Lis Hellénius 《PloS one》2015,10(11)
Background
In 1988, a cardiovascular prevention program which combined an individual and a population-based strategy was launched within primary health-care in Sollentuna, a municipality in Stockholm County. The aim of this study was to investigate time trends in the incidence of and mortality from acute myocardial infarction and all-cause mortality in Sollentuna compared with the rest of Stockholm County during a period of two decades following the implementation of a cardiovascular prevention program.Materials and Methods
The average population in Sollentuna was 56,589 (49% men) and in Stockholm County (Sollentuna included) 1,795,504 (49% men) during the study period of 1987–2010. Cases of hospitalized acute myocardial infarction and death were obtained for the population of Sollentuna and the rest of Stockholm County using national registries of hospital discharges and deaths. Acute myocardial infarction incidence and mortality were estimated using the average population of Sollentuna and Stockholm in 1987–2010.Results
During the observation period, the incidence of acute myocardial infarction decreased more in Sollentuna compared with the rest of Stockholm County in women (-22% vs. -7%; for difference in slope <0.05). There was a trend towards a greater decline in Sollentuna compared to the rest of Stockholm County in the incidence of acute myocardial infarction (in men), acute myocardial mortality, and all-cause mortality but the differences were not significant.Conclusion
During a period of steep decline in acute myocardial infarction incidence and mortality in Stockholm County the municipality of Sollentuna showed a stronger trend in women possibly compatible with favorable influence of a cardiovascular prevention program.Trial Registration
ClinicalTrials.gov NCT02212145 相似文献45.
Jonathan Nambiar Adam W Clarke Doris Shim David Mabon Chen Tian Karolina Windloch Chris Buhmann Beau Corazon Matilda Lindgren Matthew Pollard Teresa Domagala Lynn Poulton Anthony G Doyle 《MABS-AUSTIN》2015,7(3):638-650
CD1d is a receptor on antigen-presenting cells involved in triggering cell populations, particularly natural killer T (NKT) cells, to release high levels of cytokines. NKT cells are implicated in asthma pathology and blockade of the CD1d/NKT cell pathway may have therapeutic potential. We developed a potent anti-human CD1d antibody (NIB.2) that possesses high affinity for human and cynomolgus macaque CD1d (KD ∼100 pM) and strong neutralizing activity in human primary cell-based assays (IC50 typically <100 pM). By epitope mapping experiments, we showed that NIB.2 binds to CD1d in close proximity to the interface of CD1d and the Type 1 NKT cell receptor β-chain. Together with data showing that NIB.2 inhibited stimulation via CD1d loaded with different glycolipids, this supports a mechanism whereby NIB.2 inhibits NKT cell activation by inhibiting Type 1 NKT cell receptor β-chain interactions with CD1d, independent of the lipid antigen in the CD1d antigen-binding cleft. The strong in vitro potency of NIB.2 was reflected in vivo in an Ascaris suum cynomolgus macaque asthma model. Compared with vehicle control, NIB.2 treatment significantly reduced bronchoalveolar lavage (BAL) levels of Ascaris-induced cytokines IL-5, IL-8 and IL-1 receptor antagonist, and significantly reduced baseline levels of GM-CSF, IL-6, IL-15, IL-12/23p40, MIP-1α, MIP-1β, and VEGF. At a cellular population level NIB.2 also reduced numbers of BAL lymphocytes and macrophages, and blood eosinophils and basophils. We demonstrate that anti-CD1d antibody blockade of the CD1d/NKT pathway modulates inflammatory parameters in vivo in a primate inflammation model, with therapeutic potential for diseases where the local cytokine milieu is critical. 相似文献
46.
J. K. Lindgren V. C. Thomas M. E. Olson S. S. Chaudhari A. S. Nuxoll C. R. Schaeffer K. E. Lindgren J. Jones M. C. Zimmerman P. M. Dunman K. W. Bayles P. D. Fey 《Journal of bacteriology》2014,196(12):2277-2289
Allelic replacement mutants were constructed within arginine deiminase (arcA1 and arcA2) to assess the function of the arginine deiminase (ADI) pathway in organic acid resistance and biofilm formation of Staphylococcus epidermidis 1457. A growth-dependent acidification assay (pH ∼5.0 to ∼5.2) determined that strain 1457 devoid of arginine deiminase activity (1457 ΔADI) was significantly less viable than the wild type following depletion of glucose and in the presence of arginine. However, no difference in viability was noted for individual 1457 ΔarcA1 (native) or ΔarcA2 (arginine catabolic mobile element [ACME]-derived) mutants, suggesting that the native and ACME-derived ADIs are compensatory in S. epidermidis. Furthermore, flow cytometry and electron paramagnetic resonance spectroscopy results suggested that organic acid stress resulted in oxidative stress that could be partially rescued by the iron chelator dipyridyl. Collectively, these results suggest that formation of hydroxyl radicals is partially responsible for cell death via organic acid stress and that ADI-derived ammonia functions to counteract this acid stress. Finally, static biofilm assays determined that viability, ammonia synthesis, and pH were reduced in strain 1457 ΔADI following 120 h of growth in comparison to strain 1457 and the arcA1 and arcA2 single mutants. It is hypothesized that ammonia synthesis via the ADI pathway is important to reduce pH stress in specific microniches that contain high concentrations of organic acids. 相似文献
47.
Species with a wide distribution over latitudinal gradients often exhibit increasing growth and development rates towards
higher latitudes. Ecological theory predicts that these fast-growing genotypes are, in the absence of trade-offs with fast
growth, better competitors than low-latitude conspecifics. While knowledge on key ecological traits along latitudinal clines
is important for understanding how these clines are maintained, the relative competitive ability of high latitude individuals
against low latitude conspecifics has not been tested. Growth and development rates of the common frog Rana temporaria increase along the latitudinal gradient across Scandinavia. Here we investigated larval competition over food resources within
and between two R. temporaria populations originating from southern and northern Sweden in an outdoor common garden experiment. We used a factorial design,
where southern and northern tadpoles were reared either as single populations or as mixes of the two populations at two densities
and predator treatments (absence and non-lethal presence of Aeshna dragonfly larvae). Tadpoles from the high latitude population grew and developed faster and in the beginning of the experiment
they hid less and were more active than tadpoles from the low latitude population. When raised together with high latitude
tadpoles the southern tadpoles had a longer larval period, however, the response of high latitude tadpoles to the competition
by low latitude tadpoles did not differ from their response to intra-population competition. This result was not significantly
affected by density or predator treatments. Our results support the hypothesis that high latitude populations are better competitors
than their low latitude conspecifics, and suggest that in R. temporaria fast growth and development trade off with other fitness components along the latitudinal gradient across Scandinavia. 相似文献
48.
This article explores to what extent married middle-aged individuals in Europe are governed by the risk of experiencing divorce, when shaping their physical appearance. The main result is that divorce risks, proxied by national divorce rates, are negatively connected to body mass index (BMI) among married individuals but unrelated to BMI among singles. Hence, it seems that married people in societies where divorce risks are high are more inclined to invest in their outer appearance. One interpretation is that high divorce rates make married people prepare for a potential divorce and future return to the marriage market. 相似文献
49.
50.
The concept of a Barcode of Life Database (BoLD) for the Class Cephalopoda (Phylum Mollusca) was introduced at the Cephalopod
International Advisory Council (CIAC) symposium in Hobart, Australia, February 2006. This suggestion was met with significant
interest, concern and debate. This review attempts to describe the concept of the BoLD initiative and to outline considerations
and concerns specific to a cephalopod BoLD.
Jan M. Strugnell and Annie R. Lindgren contributed equally to this work. 相似文献