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1.
Biochemical pathways in prokaryotes can be traced backward through evolutionary time 总被引:10,自引:0,他引:10
For the first time, a credible prokaryotic phylogenetic tree is being
assembled by Woese and others using quantitative sequence analysis of
oligonucleotides in the highly conservative rRNA. This provides an
evolutionary scale against which the evolutionary steps that led to the
arrangement and regulation of contemporary biochemical pathways can be
measured. This paper presents an emerging evolutionary picture of aromatic
amino acid biosynthesis within a large superfamily assemblage of
prokaryotes that is sufficiently developed to illustrate a new perspective
that will be applicable to many other biochemical pathways.
相似文献
2.
3.
MARIA JOSÉ ASINS IRENE VILLALTA MOHAMED M. ALY RAQUEL OLÍAS PAZ ÁLVAREZ DE MORALES RAÚL HUERTAS JUN LI NOELIA JAIME‐PÉREZ ROSARIO HARO VERÓNICA RAGA EMILIO A. CARBONELL ANDRÉS BELVER 《Plant, cell & environment》2013,36(6):1171-1191
The location of major quantitative trait loci (QTL) contributing to stem and leaf [Na+] and [K+] was previously reported in chromosome 7 using two connected populations of recombinant inbred lines (RILs) of tomato. HKT1;1 and HKT1;2, two tomato Na+‐selective class I‐HKT transporters, were found to be closely linked, where the maximum logarithm of odds (LOD) score for these QTLs located. When a chromosome 7 linkage map based on 278 single‐nucleotide polymorphisms (SNPs) was used, the maximum LOD score position was only 35 kb from HKT1;1 and HKT1;2. Their expression patterns and phenotypic effects were further investigated in two near‐isogenic lines (NILs): 157‐14 (double homozygote for the cheesmaniae alleles) and 157‐17 (double homozygote for the lycopersicum alleles). The expression pattern for the HKT1;1 and HKT1;2 alleles was complex, possibly because of differences in their promoter sequences. High salinity had very little effect on root dry and fresh weight and consequently on the plant dry weight of NIL 157‐14 in comparison with 157‐17. A significant difference between NILs was also found for [K+] and the [Na+]/[K+] ratio in leaf and stem but not for [Na+] arising a disagreement with the corresponding RIL population. Their association with leaf [Na+] and salt tolerance in tomato is also discussed. 相似文献
4.
The K+/H+ antiporter LeNHX2 increases salt tolerance by improving K+ homeostasis in transgenic tomato 总被引:1,自引:0,他引:1
RAÚL HUERTAS LOURDES RUBIO OLIVIER CAGNAC MARÍA JESÚS GARCÍA‐SÁNCHEZ JUAN DE DIOS ALCHÉ KEES VENEMA JOSÉ ANTONIO FERNÁNDEZ MARÍA PILAR RODRÍGUEZ‐ROSALES 《Plant, cell & environment》2013,36(12):2135-2149
The endosomal LeNHX2 ion transporter exchanges H+ with K+ and, to lesser extent, Na+. Here, we investigated the response to NaCl supply and K+ deprivation in transgenic tomato (Solanum lycopersicum L.) overexpressing LeNHX2 and show that transformed tomato plants grew better in saline conditions than untransformed controls, whereas in the absence of K+ the opposite was found. Analysis of mineral composition showed a higher K+ content in roots, shoots and xylem sap of transgenic plants and no differences in Na+ content between transgenic and untransformed plants grown either in the presence or the absence of 120 mm NaCl. Transgenic plants showed higher Na+/H+ and, above all, K+/H+ transport activity in root intracellular membrane vesicles. Under K+ limiting conditions, transgenic plants enhanced root expression of the high‐affinity K+ uptake system HAK5 compared to untransformed controls. Furthermore, tomato overexpressing LeNHX2 showed twofold higher K+ depletion rates and half cytosolic K+ activity than untransformed controls. Under NaCl stress, transgenic plants showed higher uptake velocity for K+ and lower cytosolic K+ activity than untransformed plants. These results indicate the fundamental role of K+ homeostasis in the better performance of LeNHX2 overexpressing tomato under NaCl stress. 相似文献
5.
The application of sensory methodology for measuring deodorizing effect of an air conditioner equipped with electric plasma was introduced. Deodorizing effect was measured using chemical and sensory methods at different time (0, 30 and 60 min) and mode (control, blowing and cooling) of an air conditioner. Smoke from a roll of cigarette in a closed room was used as a source of odor and the concentrations of acetic acid and ammonia were measured as odorous chemical components. As one of the sensory methods triangle test was used and as a first step to obtain deodorizing effects by triangle test, the threshold of each panelist was obtained as the log dilution ratio of odor concentration at which the difference from odorless air was detected. The odor concentration at each time and mode was calculated using the threshold of the panel and the deodorizing effect was obtained on the basis of the odor concentration. In addition to a triangle test, scaling methods such as category scaling or magnitude estimation were used to measure deodorizing effect of an air conditioner. Deodorizing effects by scaling methods were calculated based on odor intensity with time at each mode. The regression analysis was done between the efficacy of deodorizing effect by sensory test and those by acetic acid and ammonia, the R2 values of the regression equations for triangle test, category scale, and magnitude estimation were 0.84, 0.72 and 0.69, respectively. Deodorizing effect by triangle test explained the decrease of acetic acid and ammonia better than those by category scaling or magnitude estimation while high cost and time consuming labor involved in triangle tests reduced the merit. The results of this study demonstrated that various sensory methods could be used to measure deodorizing effect of air conditioners and further researches on fast and reliable methods are needed to establish the official procedures. 相似文献
6.
Background
The analysis of genetic variation in populations of infectious agents may help us understand their epidemiology and evolution. Here we study a model for assessing the levels and patterns of genetic diversity in populations of infectious agents. The population is structured into many small subpopulations, which correspond to their hosts, that are connected according to a specific type of contact network. We considered different types of networks, including fully connected networks and scale free networks, which have been considered as a model that captures some properties of real contact networks. Infectious agents transmit between hosts, through migration, where they grow and mutate until elimination by the host immune system. 相似文献7.
AIMS: Adoption of the property of cytidine (cytosine-beta-d-riboside) deamination in staphylococci to distinguish Staphylococcus aureus from other staphylococci. METHODS AND RESULTS: A total of 560 staphylococcal strains were examined. The test demonstrated a sensitivity of 97.1% and a specificity of 98.8%. Of the 249 S. aureus strains (115 oxacillin-resistant) 58 strains were coagulase-negative S. aureus and another 16 strains were clumping factor-negative S. aureus. The 74 deficient S. aureus strains were identified by 16S rRNA gene sequencing and further investigated by spa typing and 13 spa types were found. CONCLUSIONS: The cytidine deaminase test (CDT) is useful especially for distinguishing coagulase- and clumping factor-negative S. aureus from other staphylococci and the results correlated well with 16S rRNA sequencing and the polymerase chain reaction (PCR) amplification of the nuc gene. SIGNIFICANCE AND IMPACT OF THE STUDY: Cytidine deamination assay differentiates S. aureus from other staphylococci. This method is fast (6 h) and reliable in distinguishing between non-S. aureus and the defective (coagulase-negative, clumping factor-negative) S. aureus isolates which could have major consequences for therapy. 相似文献
8.
9.
Phylogenetic utility of the nuclear gene arginine decarboxylase: an example from Brassicaceae 总被引:8,自引:2,他引:8
Arginine decarboxylase (ADC) is an important enzyme in the production of
putrescine and polyamines in plants. It is encoded by a single or low-copy
nuclear gene that lacks introns in sequences studied to date. The rate of
Adc amino acid sequence evolution is similar to that of ndhF for the
angiosperm family studied. Highly conserved regions provide several target
sites for PCR priming and sequencing and aid in nucleotide and amino acid
sequence alignment across a range of taxonomic levels, while a variable
region provides an increased number of potentially informative characters
relative to ndhF for the taxa surveyed. The utility of the Adc gene in
plant molecular systematic studies is demonstrated by analysis of its
partial nucleotide sequences obtained from 13 representatives of
Brassicaceae and 3 outgroup taxa, 2 from the mustard oil clade (order
Capparales) and 1 from the related order Malvales. Two copies of the Adc
gene, Adc1 and Adc2, are found in all members of the Brassicaceae studied
to data except the basal genus Aethionema. The resulting Adc gene tree
provides robust phylogenetic data regarding relationships within the
complex mustard family, as well as independent support for proposed tribal
realignments based on other molecular data sets such as those from
chloroplast DNA.
相似文献
10.
BACKGROUND: Granulomatous inflammation of the breast is an inflammatory process with multiple etiologies. It can accompany breast carcinoma or be idiopathic. It often presents clinically in a fashion mimicking carcinoma. Idiopathic granulomatous mastitis is strongly associated with lactation and is reported to occur in postpartum patients. This is the second fine needle aspiration (FNA) report of idiopathic granulomatous inflammation in the breast of a pregnant woman. CASE: A 27-year-old, 7-month-pregnant woman presented with a hard nodule in her right breast; on ultrasound examination it showed mixed echogenicity, suspicious for carcinoma. FNA showed granulomatous inflammation. The smears were highly cellular, with many clusters of and single epithelioid cells displaying moderate pleomorphism and prominent nucleoli in a background composed of neutrophils, plasma cells, lymphocytes and multinucleated cells. Core needle biopsy revealed a nonnecrotizing, granulomatous lesion. CONCLUSION: The diagnosis of granulomatous inflammation can be challenging, and the cytologic features can be difficult to separate from those of carcinoma. The relatively rare occurrence of this lesion and its cytologic features make it a potentially difficult diagnosis and diagnostic pitfall. 相似文献