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排序方式: 共有296条查询结果,搜索用时 15 毫秒
41.
Lucas A. Cernusak Margaret M. Barbour Stefan K. Arndt Alexander W. Cheesman Nathan B. English Taylor S. Feild Brent R. Helliker Meisha M. Holloway‐Phillips Joseph A.M. Holtum Ansgar Kahmen Francesca A. McInerney Niels C. Munksgaard Kevin A. Simonin Xin Song Hilary Stuart‐Williams Jason B. West Graham D. Farquhar 《Plant, cell & environment》2016,39(5):1087-1102
Leaf water contains naturally occurring stable isotopes of oxygen and hydrogen in abundances that vary spatially and temporally. When sufficiently understood, these can be harnessed for a wide range of applications. Here, we review the current state of knowledge of stable isotope enrichment of leaf water, and its relevance for isotopic signals incorporated into plant organic matter and atmospheric gases. Models describing evaporative enrichment of leaf water have become increasingly complex over time, reflecting enhanced spatial and temporal resolution. We recommend that practitioners choose a model with a level of complexity suited to their application, and provide guidance. At the same time, there exists some lingering uncertainty about the biophysical processes relevant to patterns of isotopic enrichment in leaf water. An important goal for future research is to link observed variations in isotopic composition to specific anatomical and physiological features of leaves that reflect differences in hydraulic design. New measurement techniques are developing rapidly, enabling determinations of both transpired and leaf water δ18O and δ2H to be made more easily and at higher temporal resolution than previously possible. We expect these technological advances to spur new developments in our understanding of patterns of stable isotope fractionation in leaf water. 相似文献
42.
Bradley E. Jackson V. K. Bhupathiraju Ralph S. Tanner Carl R. Woese M. J. McInerney 《Archives of microbiology》1999,171(2):107-114
Strain SBT is a new, strictly anaerobic, gram-negative, nonmotile, non-sporeforming, rod-shaped bacterium that degrades benzoate and
certain fatty acids in syntrophic association with hydrogen/formate-using microorganisms. Strain SBT produced approximately 3 mol of acetate and 0.6 mol of methane per mol of benzoate in coculture with Methanospirillum hungatei strain JF1. Saturated fatty acids, some unsaturated fatty acids, and methyl esters of butyrate and hexanoate also supported
growth of strain SBT in coculture with Desulfovibrio strain G11. Strain SBT grew in pure culture with crotonate, producing acetate, butyrate, caproate, and hydrogen. The molar growth yield was 17 ±
1 g cell dry mass per mol of crotonate. Strain SBT did not grow with fumarate, iron(III), polysulfide, or oxyanions of sulfur or nitrogen as electron acceptors with benzoate
as the electron donor. The DNA base composition of strain SBT was 43.1 mol% G+C. Analysis of the 16 S rRNA gene sequence placed strain SBT in the δ-subdivision of the Proteobacteria, with sulfate-reducing bacteria. Strain SBT was most closely related to members of the genus Syntrophus. The clear phenotypic and genotypic differences between strain SBT and the two described species in the genus Syntrophus justify the formation of a new species, Syntrophus aciditrophicus.
Received: 2 June 1998 / Accepted: 16 November 1998 相似文献
43.
Jamil M Neto Marina GM Viturino Galina Ananina Flvia F Bajano Sueli M da S Costa Alicia B Roque Gessica FS Borges Raissa Franchi Priscila HH Rim Flvio M Medina Fernando F Costa Mnica B de Melo Jos PC de Vasconcellos 《Experimental biology and medicine (Maywood, N.J.)》2021,246(21):2290
This study aimed to investigate the association among genetic variants of the complement pathway CFB R32Q (rs641153), C3 R102G (rs2230199), and CFH (rs1410996) with age-related macular degeneration (AMD) in a sample of the Brazilian population. In a case-control study, 484 AMD patients were classified according to the clinical age-related maculopathy grading system (CARMS) and compared to 479 unrelated controls. The genetic variants rs1410996 of complement H (CFH), rs641153 of complement factor B (CFB), and rs2230199 of complement 3 (C3) were evaluated through polymerase chain reaction (PCR) and direct sequencing. The associations between single nucleotide polymorphisms (SNPs) and AMD, adjusted by age, were assessed by using logistic regression models. A statistically significant association was observed between AMD risk and rs2230199 variant with an OR of 2.01 (P = 0.0002) for CG individuals compared to CC individuals. Regarding the comparison of advanced AMD versus the control group, the OR was 2.12 (P = 0.0036) for GG versus AA genotypes for rs1410996 variant. Similarly, the OR for rs2230199 polymorphism was 2.3034 (P = 5.47e-05) when comparing CG individuals to CC carriers. In contrast, the rs641153 variant showed a significant protective effect against advanced AMD for GA versus GG genotype (OR = 0.4406; P = 0.0019). When comparing wet AMD versus controls, a significant association was detected for rs1410996 variant (OR = 2.16; P = 0.0039) comparing carriers of the homozygous GG versus AA genotype, as well as in the comparisons of GG (OR = 3.0713; P = 0.0046) and CG genotypes (OR = 2.2249; P = 0.0002) versus CC genotype for rs2230199 variant, respectively. The rs641153 variant granted a significant protective effect against wet AMD for GA versus GG genotypes (OR = 0.4601; P = 0.0044). Our study confirmed the risk association between rs2230199 and rs1410996 variants and AMD, and the protective role against AMD for rs641153 variant. 相似文献
44.
Stefan Caddy‐Retalic Alan N. Andersen Michael J. Aspinwall Martin F. Breed Margaret Byrne Matthew J. Christmas Ning Dong Bradley J. Evans Damien A. Fordham Greg R. Guerin Ary A. Hoffmann Alice C. Hughes Stephen J. van Leeuwen Francesca A. McInerney Suzanne M. Prober Maurizio Rossetto Paul D. Rymer Dorothy A. Steane Glenda M. Wardle Andrew J. Lowe 《Ecology and evolution》2017,7(13):4607-4619
Transects that traverse substantial climate gradients are important tools for climate change research and allow questions on the extent to which phenotypic variation associates with climate, the link between climate and species distributions, and variation in sensitivity to climate change among biomes to be addressed. However, the potential limitations of individual transect studies have recently been highlighted. Here, we argue that replicating and networking transects, along with the introduction of experimental treatments, addresses these concerns. Transect networks provide cost‐effective and robust insights into ecological and evolutionary adaptation and improve forecasting of ecosystem change. We draw on the experience and research facilitated by the Australian Transect Network to demonstrate our case, with examples, to clarify how population‐ and community‐level studies can be integrated with observations from multiple transects, manipulative experiments, genomics, and ecological modeling to gain novel insights into how species and systems respond to climate change. This integration can provide a spatiotemporal understanding of past and future climate‐induced changes, which will inform effective management actions for promoting biodiversity resilience. 相似文献
45.
In methanogenic environments, the main fate of benzoate is its oxidization to acetate, H(2) and CO(2) by syntrophic associations of hydrogen-producing benzoate degraders and hydrogen-using methanogens. Here, we report the use of benzoate as an electron acceptor. Pure cultures of S. aciditrophicus simultaneously degraded crotonate and benzoate when both substrates were present. The growth rate was 0.007 h(-1) with crotonate and benzoate present compared with 0.025 h(-1) with crotonate alone. After 8 days of incubation, 4.12 +/- 0.50 mM of cyclohexane carboxylate and 8.40 +/- 0.61 mM of acetate were formed and 4.0 +/- 0.04 mM of benzoate and 4.8 +/- 0.5 mM of crotonate were consumed. The molar growth yield was 22.7 +/- 2.1 g (dry wt) of cells per mol of crotonate compared with about 14.0 +/- 0.1 g (dry wt) of cells per mol of crotonate when S. aciditrophicus was grown with crotonate alone. Cultures grown with [ring-(13)C]-benzoate and unlabelled crotonate initially formed [ring-(13)C]-labelled cyclohexane carboxylate. No (13)C-labelled acetate was detected. In addition to cyclohexane carboxylate, (13)C-labelled cyclohex-1-ene carboxylate was detected as an intermediate. Once almost all of the benzoate was gone, carbon isotopic analyses showed that cyclohexane carboxylate was formed from both labelled and non-labelled metabolites. Glutarate and pimelate were also detected at this time and carbon isotopic analyses showed that each was made from a mixture labelled and non-labelled metabolites. The increase in molar growth yield with crotonate and benzoate and the formation of [ring-(13)C]-cyclohexane carboxylate from [ring-(13)C]-benzoate in the presence of crotonate are consistent with benzoate serving as an electron acceptor. 相似文献
46.
Luciane Mendes Hatadani James O. McInerney Hermes Fonseca de Medeiros Ana Carolina Martins Junqueira Ana Maria de Azeredo-Espin Louis Bernard Klaczko 《Molecular phylogenetics and evolution》2009,51(3):595-600
We suggest a new phylogenetic hypothesis for the tripunctata radiation based on sequences of mitochondrial genes. Phylogenetic trees were reconstructed by parsimony, maximum likelihood and Bayesian methods. We performed tests for hypotheses of monophyly for taxonomic groups and other specific hypotheses. Results reject the monophyly for the tripunctata group whereas monophyly is not rejected for the tripunctata radiation and other specific groups within the radiation. Although most of the basal nodes were unresolved we were able to identify four clusters within the tripunctata radiation. These results suggest the collection of additional data before a proper taxonomic revision could be proposed. 相似文献
47.
48.
Pieter Stolk Harald E Heemstra Hubert GM Leufkens Brigitte Bloechl-Daum Eibert R Heerdink 《Orphanet journal of rare diseases》2009,4(1):1-7
Background
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease, which rapidly leads to chronic respiratory failure requiring mechanical ventilation. Currently, forced vital capacity (FVC) < 50% is considered as physiologic marker for admitting patients to Noninvasive Positive Pressure Ventilation (NPPV) intervention, although it has been recently shown the median survival of patients with baseline FVC < 75% much shorter than median survival of patients with baseline FVC > 75%, independently by any treatment.Aim
To assess the role of NPPV in improving outcome of ALS, a retrospective analysis was performed to investigate 1 year survival of ALS patients with FVC < 75% and nocturnal respiratory insufficiency, treated with NPPV, compared to a well-matched population of ALS patients, who refused or was intolerant to NPPV.Methods
We investigated seventy-two consecutive ALS patients who underwent pulmonary function test. Forty-four presented a FVC > 75% and served as control group. Twenty-eight patients presented a FVC < 75% and showed, at polysomnography analysis, nocturnal respiratory insufficiency, requiring NPPV; sixteen were treated with NPPV, while twelve refused or were intolerant.Results
Increased survival rate at 1 year in patients with FVC < 75% treated with NPPV, as compared to those who refused or could not tolerate NPPV (p = 0.02), was observed. The median rate of decline in FVC% was slower in NPPV patients than in patients who did not use NPPV (95% CI: 0.72 to 1.85; p < 0.0001).Conclusion
This report demonstrates that early treatment with NPPV prolongs survival and reduces decline of FVC% in ALS. 相似文献49.
Caitríona E. McInerney A. Louise Allcock Mark P. Johnson Paulo A. Prodöhl 《Conservation Genetics》2009,10(5):1417-1420
Eight polymorphic microsatellite loci are described for Littorina littorea (Linnaeus, 1758). Data on allelic variation in Irish and Celtic Sea samples are reported. The average number of alleles per
locus was 11 (range 4–29), and observed and expected heterozygosities ranged from 6.9 to 84.3% and from 9.4 to 95.2%, respectively.
Loci did not deviate from Hardy–Weinberg equilibrium and no linkage disequilibrium between loci pairs was detected. Microsatellites
were not highly conserved in the congeners, L. fabalis, L. saxatilis, L. compressa and L. obtusata as evidenced by a low rate of cross-amplification. These microsatellites should prove useful in population genetic studies. 相似文献
50.
Sieber JR Sims DR Han C Kim E Lykidis A Lapidus AL McDonnald E Rohlin L Culley DE Gunsalus R McInerney MJ 《Environmental microbiology》2010,12(8):2289-2301
Syntrophomonas wolfei is a specialist, evolutionarily adapted for syntrophic growth with methanogens and other hydrogen- and/or formate-using microorganisms. This slow-growing anaerobe has three putative ribosome RNA operons, each of which has 16S rRNA and 23S rRNA genes of different length and multiple 5S rRNA genes. The genome also contains 10 RNA-directed, DNA polymerase genes. Genomic analysis shows that S. wolfei relies solely on the reduction of protons, bicarbonate or unsaturated fatty acids to re-oxidize reduced cofactors. Syntrophomonas wolfei lacks the genes needed for aerobic or anaerobic respiration and has an exceptionally limited ability to create ion gradients. An ATP synthase and a pyrophosphatase were the only systems detected capable of creating an ion gradient. Multiple homologues for β-oxidation genes were present even though S. wolfei uses a limited range of fatty acids from four to eight carbons in length.Syntrophomonas wolfei, other syntrophic metabolizers with completed genomic sequences, and thermophilic anaerobes known to produce high molar ratios of hydrogen from glucose have genes to produce H(2) from NADH by an electron bifurcation mechanism. Comparative genomic analysis also suggests that formate production from NADH may involve electron bifurcation. A membrane-bound, iron-sulfur oxidoreductase found in S. wolfei and Syntrophus aciditrophicus may be uniquely involved in reverse electron transport during syntrophic fatty acid metabolism. The genome sequence of S. wolfei reveals several core reactions that may be characteristic of syntrophic fatty acid metabolism and illustrates how biological systems produce hydrogen from thermodynamically difficult reactions. 相似文献