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Codon fitnesses for chloroplast genes were estimated using the relative
synonymous codon use of psbA, which has a different pattern of codon use
than other chloroplast genes and is the major translation product of the
chloroplast. These estimates were used to calculate the codon adaptation
index (CAI) of chloroplast genes from Marchantia polymorpha, Nicotiana
tabacum, and Chlamydomonas reinhardtii. The genes with the highest CAI
values in M. polymorpha correspond to those that are expressed at the
highest levels. The rate of divergence between M. polymorpha and both C.
reinhardtii and N. tabacum is inversely related to the CAI value of the M.
polymorpha gene. The data suggest that selection is acting on the
synonymous codon use of the highly expressed genes of the M. polymorpha
chloroplast genome. The data set is inconclusive about N. tabacum genes,
but, as there is a weaker correspondence between CAI value and expression
level, it suggests that selection is not operating in this lineage.
相似文献
33.
Molecular phylogenetic and biogeochemical studies of sulfate-reducing bacteria in the rhizosphere of spartina alterniflora 总被引:1,自引:0,他引:1
Hines ME Evans RS Sharak Genthner BR Willis SG Friedman S Rooney-Varga JN Devereux R 《Applied and environmental microbiology》1999,65(5):2209-2216
The population composition and biogeochemistry of sulfate-reducing bacteria (SRB) in the rhizosphere of the marsh grass Spartina alterniflora was investigated over two growing seasons by molecular probing, enumerations of culturable SRB, and measurements of SO42- reduction rates and geochemical parameters. SO42- reduction was rapid in marsh sediments with rates up to 3.5 &mgr;mol ml-1 day-1. Rates increased greatly when plant growth began in April and decreased again when plants flowered in late July. Results with nucleic acid probes revealed that SRB rRNA accounted for up to 43% of the rRNA from members of the domain Bacteria in marsh sediments, with the highest percentages occurring in bacteria physically associated with root surfaces. The relative abundance (RA) of SRB rRNA in whole-sediment samples compared to that of Bacteria rRNA did not vary greatly throughout the year, despite large temporal changes in SO42- reduction activity. However, the RA of root-associated SRB did increase from <10 to >30% when plants were actively growing. rRNA from members of the family Desulfobacteriaceae comprised the majority of the SRB rRNA at 3 to 34% of Bacteria rRNA, with Desulfobulbus spp. accounting for 1 to 16%. The RA of Desulfovibrio rRNA generally comprised from <1 to 3% of the Bacteria rRNA. The highest Desulfobacteriaceae RA in whole sediments was 26% and was found in the deepest sediment samples (6 to 8 cm). Culturable SRB abundance, determined by most-probable-number analyses, was high at >10(7) ml-1. Ethanol utilizers were most abundant, followed by acetate utilizers. The high numbers of culturable SRB and the high RA of SRB rRNA compared to that of Bacteria rRNA may be due to the release of SRB substrates in plant root exudates, creating a microbial food web that circumvents fermentation. 相似文献
34.
Challa BR Awen BZ Chandu BR Rihanaparveen S 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2011,879(11-12):769-776
Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) was used for a quantitative estimation of entecavir (EV) in human plasma using lamivudine (LM) as internal standard (IS). The method herein described is simple, sensitive, and specific. Chromatographic separation was performed on XBridge-C18, 4.6 mm × 50 mm, 5-μm column with an isocratic mobile phase composed of 10 mM ammonium hydrogen carbonate (pH 10.5):methanol (85:15 v/v), pumped at 0.3 ml/min. EV and LM were detected using proton adducts at m/z 278.1→152.1 and 230.2→112.0 in multiple reaction monitoring (MRM) positive mode. Solid phase extraction method was employed in the extraction of EV and LM from the biological matrix. This method was validated over a linear concentration range of 50.0-20000.0 pg/ml with a correlation coefficient (r) ≥0.9983. Intra and inter-day precision of EV was found within the range of 1.2-4.2 for EV and 4.4-4.5 for LM. EV was stable throughout three freeze/thaw cycles, bench top and postoperative studies. This method was successfully used in the analysis of plasma samples following oral administration of EV (0.5 mg) in 26 healthy human volunteers. 相似文献
35.
B Nagy BR Watters PDW van der Merwe FPD Cotterill DU Bellstedt 《African Journal of Aquatic Science》2017,42(3):201-218
Nothobranchius cooperi, Nagy, Watters and Bellstedt, new species, is described from seasonal streams and ephemeral pools associated with the upper Mansa River system in the middle Luapula drainage and systems draining into the low-lying area marginal to the southwestern part of Lake Bangweulu, in the Luapula province of northern Zambia. It belongs to the N. brieni species group. Males of Nothobranchius cooperi are distinguished from congeners by the following unique combination of characters: body scales with broad orange posterior margin, forming a highly irregular cross-barred pattern; anal fin fairly uniform orange-red with irregular to regular, light blue-green zone close to the base; caudal peduncle length 1.2–1.3 times its depth; prepelvic length 48.8–51.9% SL; and head depth 75–77% of head length. Genetic divergence of the mitochondrial COI and ND2 genes and nuclear S7 gene support the distinction of the new species from its closest known relative, N. rosenstocki and confirms its position in the N. brieni species group. 相似文献
36.
Alien fishes are considered a major threat to aquatic biodiversity in South Africa, yet relatively little regional information on their biology and ecology is available for many of these species. Seasonal changes in the diet of the bluegill Lepomis macrochirus in Howieson’s Poort Dam, Grahamstown, were assessed during summer and winter in 2014–2015, using stomach content analysis. In winter, juvenile and adult fish diets were dominated by crustacean zooplankton and insects, respectively. In summer, juvenile fish fed on crustaceans and insects, whereas adults consumed mostly fish eggs, indicating a potential impact by these invasive fish on native fish through oophagy. 相似文献
37.
Dey G Palit S Banerjee R Maiti BR 《Journal of industrial microbiology & biotechnology》2002,28(4):193-200
A maltooligosaccharide-forming amylase that hydrolyzes starch into maltotriose and maltopentaose was found in the culture
filtrate of a strain of Bacillus circulans GRS 313 isolated from local soil. The enzyme was purified by organic solvent fractionation, Sephadex G-100 gel filtration
and CM-Sephadex column chromatography. Optimum pH and temperature of amylase were evaluated using response surface methodology
(RSM) and were found to be 48°C and 4.9, respectively. The enzyme was stable up to 60°C and its pH stability was in the range
of 5.0–8.0. The K
m and V
max of the amylase with starch were 11.66 mg/ml and 68.97 U, respectively, and the energy of activation, E
a, was 7.52 kcal/mol. Dextrin inhibited the enzyme competitively, with a K
i of 6.1 mg/ml, and glucose caused noncompetitive inhibition with a K
i of 9.5 mg/ml. The enzyme was inhibited by Hg2+, Mn2+, Fe3+ and Cu2+ and enhanced by Co2+ and Mg2+. EDTA reversed the inhibitory effect of the metals. Paper chromatographic and high-performance liquid chromatography analysis
of the products of the amylolytic reaction showed the presence of maltotriose, maltotetraose, maltopentaose, maltose and glucose
in the starch hydrolysate. Journal of Industrial Microbiology & Biotechnology (2002) 28, 193–200 DOI: 10.1038/sj/jim/7000220
Received 11 December 2000/ Accepted in revised form 22 October 2001 相似文献
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Ian R Mackenzie Stefanie L Butland Rebecca S Devon Emily Dwosh Howard Feldman Caroline Lindholm Scott J Neal Francis BR Ouellette Blair R Leavitt 《BMC neurology》2006,6(1):32-7