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1.
Longest root elongation diminished significantly in the three species tested from 6 mm d-1 to 3 mm d-1 in 3 weeks. During this period S.D. increased considerably (from 49% to 112%, A. castellana), and accounted on the average for 68% (A. capillaris) till 94% (A. castellana) of the mean. Maximum root growth stabilized at 6 mm d-1 and showed less variation in the measurements (S.D. 52% of the mean). Growth of the originally longest root approaches zero in all three species, in accordance with the natural cease of growth of roots in grasses fascicular root system. Measuring maximum root growth instead of longest root elongation is proposed for testing metal tolerance of grasses in sequential experiments. 相似文献
2.
Treatment of H2S using a horizontal biotrickling filter based on biological activated carbon: reactor setup and performance evaluation 总被引:1,自引:0,他引:1
Biological treatment is an emerging and prevalent technology for treating off-gases from wastewater treatment plants. The most commonly reported odorous compound in off-gases is hydrogen sulfide (H2S), which has a very low odor threshold. A self-designed, bench-scale, cross-flow horizontal biotrickling filter (HBF) operated with bacteria immobilized activated carbon (termed biological activated carbon—BAC), was applied for the treatment of H2S. A mixed culture of sulfide-oxidizing bacteria dominated by Acidithiobacillus thiooxidans acclimated from activated sludge was used as bacterial seed and the biofilm was developed by culturing the bacteria in the presence of carbon pellets in mineral medium. HBF performance was evaluated systematically over 120 days, depending on a series of changing factors including inlet H2S concentration, gas retention time (GRT), pH of recirculation solution, upset and recovery, sulfate accumulation, pressure drop, gas-liquid ratio, and shock loading. The biotrickling filter system can operate at high efficiency from the first day of operation. At a volumetric loading of 900 m3 m–3 h–1 (at 92 ppmv H2S inlet concentration), the BAC exhibited maximum elimination capacity (113 g H2S/m–3 h–1) and a removal efficiency of 96% was observed. If the inlet concentration was kept at around 20 ppmv, high H2S removal (over 98%) was achieved at a GRT of 4 s, a value comparable with those currently reported for biotrickling filters. The bacterial population in the acidic biofilter demonstrated capacity for removal of H2S over a broad pH range (pH 1–7). A preliminary investigation into the different effects of bacterial biodegradation and carbon adsorption on system performance was also conducted. This study shows the HBF to be a feasible and economic alternative to physical and chemical treatments for the removal of H2S. 相似文献
3.
Stephen GS Vreden Jeetendra K Jitan Rakesh D Bansie Malti R Adhin 《Memórias do Instituto Oswaldo Cruz》2013,108(8):968-973
The emerging resistance to artemisinin derivatives that has been reported in
South-East Asia led us to assess the efficacy of artemether-lumefantrine as the first
line therapy for uncomplicated Plasmodium falciparum infections in
Suriname. This drug assessment was performed according to the recommendations of the
World Health Organization in 2011. The decreasing number of malaria cases in
Suriname, which are currently limited to migrating populations and gold miners,
precludes any conclusions on artemether efficacy because adequate numbers of patients
with 28-day follow-up data are difficult to obtain. Therefore, a comparison of day 3
parasitaemia in a 2011 study and in a 2005/2006 study was used to detect the
emergence of resistance to artemether. The prevalence of day 3 parasitaemia was
assessed in a study in 2011 and was compared to that in a study in 2005/2006. The
same protocol was used in both studies and artemether-lumefantrine was the study
drug. Of 48 evaluable patients in 2011, 15 (31%) still had parasitaemia on day 3
compared to one (2%) out of 45 evaluable patients in 2005/2006. Overall, 11 evaluable
patients in the 2011 study who were followed up until day 28 had negative slides and
similar findings were obtained in all 38 evaluable patients in the 2005/2006 study.
The significantly increased incidence of parasite persistence on day 3 may be an
indication of emerging resistance to artemether. 相似文献
4.
Kumaran Sivagnanam Vijaya GS Raghavan Manesh Shah Robert L Hettich Nathan C Verberkmoes Mark G Lefsrud 《Proteome science》2011,9(1):1-14
Background
Cytokinin is a plant hormone that plays a crucial role in several processes of plant growth and development. In recent years, major breakthroughs have been achieved in the elucidation of the metabolism, the signal perception and transduction, as well as the biological functions of cytokinin. An important activity of cytokinin is the involvement in chloroplast development and function. Although this biological function has already been known for 50 years, the exact mechanisms remain elusive.Results
To elucidate the effects of altered endogenous cytokinin content on the structure and function of the chloroplasts, chloroplast subfractions (stroma and thylakoids) from transgenic Pssu-ipt and 35S:CKX1 tobacco (Nicotiana tabacum) plants with, respectively, elevated and reduced endogenous cytokinin content were analysed using two different 2-DE approaches. Firstly, thykaloids were analysed by blue-native polyacrylamide gel electrophoresis followed by SDS-PAGE (BN/SDS-PAGE). Image analysis of the gel spot pattern thus obtained from thylakoids showed no substantial differences between wild-type and transgenic tobacco plants. Secondly, a quantitative DIGE analysis of CHAPS soluble proteins derived from chloroplast subfractions indicated significant gel spot abundance differences in the stroma fraction. Upon identification by MALDI-TOF/TOF mass spectrometry, these proteins could be assigned to the Calvin-Benson cycle and photoprotective mechanisms.Conclusion
Taken together, presented proteomic data reveal that the constitutively altered cytokinin status of transgenic plants does not result in any qualitative changes in either stroma proteins or protein complexes of thylakoid membranes of fully developed chloroplasts, while few but significant quantitative differences are observed in stroma proteins. 相似文献5.
Thiago?GazoniEmail author Simone?L?Gruber Ana?PZ?Silva Olivia?GS?Araújo Hideki?Narimatsu Christine?Strüssmann Célio?FB?Haddad Sanae?Kasahara 《BMC genetics》2012,13(1):109
Background
The karyotypes of Leptodactylus species usually consist of 22 bi-armed chromosomes, but morphological variations in some chromosomes and even differences in the 2n have been reported. To better understand the mechanisms responsible for these differences, eight species were analysed using classical and molecular cytogenetic techniques, including replication banding with BrdU incorporation.Results
Distinct chromosome numbers were found: 2n = 22 in Leptodactylus chaquensis, L. labyrinthicus, L. pentadactylus, L. petersii, L. podicipinus, and L. rhodomystax; 2n = 20 in Leptodactylus sp. (aff. podicipinus); and 2n = 24 in L. marmoratus. Among the species with 2n = 22, only three had the same basic karyotype. Leptodactylus pentadactylus presented multiple translocations, L. petersii displayed chromosome morphological discrepancy, and L. podicipinus had four pairs of telocentric chromosomes. Replication banding was crucial for characterising this variability and for explaining the reduced 2n in Leptodactylus sp. (aff. podicipinus). Leptodactylus marmoratus had few chromosomes with a similar banding patterns to the 2n = 22 karyotypes. The majority of the species presented a single NOR-bearing pair, which was confirmed using Ag-impregnation and FISH with an rDNA probe. In general, the NOR-bearing chromosomes corresponded to chromosome 8, but NORs were found on chromosome 3 or 4 in some species. Leptodactylus marmoratus had NORs on chromosome pairs 6 and 8. The data from C-banding, fluorochrome staining, and FISH using the telomeric probe helped in characterising the repetitive sequences. Even though hybridisation did occur on the chromosome ends, telomere-like repetitive sequences outside of the telomere region were identified. Metaphase I cells from L. pentadactylus confirmed its complex karyotype constitution because 12 chromosomes appeared as ring-shaped chain in addition to five bivalents.Conclusions
Species of Leptodactylus exhibited both major and minor karyotypic differences which were identified by classical and molecular cytogenetic techniques. Replication banding, which is a unique procedure that has been used to obtain longitudinal multiple band patterns in amphibian chromosomes, allowed us to outline the general mechanisms responsible for these karyotype differences. The findings also suggested that L. marmoratus, which was formerly included in the genus Adenomera, may have undergone great chromosomal repatterning.6.
L-Lactate dehydrogenase (L-LDH, E.C. 1.1.1.27) is encoded by two or three
loci in all vertebrates examined, with the exception of lampreys, which
have a single LDH locus. Biochemical characterizations of LDH proteins have
suggested that a gene duplication early in vertebrate evolution gave rise
to Ldh-A and Ldh-B and that an additional locus, Ldh-C arose in a number of
lineages more recently. Although some phylogenetic studies of LDH protein
sequences have supported this pattern of gene duplication, others have
contradicted it. In particular, a number of studies have suggested that
Ldh-C represents the earliest divergence among vertebrate LDHs and that it
may have diverged from the other loci well before the origin of
vertebrates. Such hypotheses make explicit statements about the
relationship of vertebrate and invertebrate LDHs, but to date, no closely
related invertebrate LDH sequences have been available for comparison. We
have attempted to provide further data on the timing of gene duplications
leading to multiple vertebrate LDHs by determining the cDNA sequence of the
LDH of the tunicate Styela plicata. Phylogenetic analyses of this and other
LDH sequences provide strong support for the duplications giving rise to
multiple vertebrate LDHs having occurred after vertebrates diverged from
tunicates. The timing of these LDH duplications is consistent with data
from a number of other gene families suggesting widespread gene duplication
near the origin of vertebrates. With respect to the relationships among
vertebrate LDHs, our data are not consistent with previous claims that
Ldh-C represented the earliest divergence. However, the precise
relationships among some of the main lineages of vertebrate LDHs were not
resolved in our analyses.
相似文献
7.
8.
Tryptophan hydroxylase inhibitors 总被引:4,自引:0,他引:4
B K Koe 《Federation proceedings》1971,30(3):886-896
9.
A better understanding of the nature of the interaction between various cationic lipids used for gene delivery and DNA would lend insight into their structural and physical properties that may modulate their efficacy. We therefore separated the protonation and binding events which occur upon complexation of 1:1 DOTAP (1,2-dioleoyl-3-trimethylammonium propane):DOPE (1,2-dioleoylphosphatidylethanolamine) liposomes to DNA using proton linkage theory and isothermal titration calorimetry (ITC). The enthalpy of DOPE protonation was estimated as -45.0+/-0.7 kJ/mol and the intrinsic binding enthalpy of lipid to DNA as +2.8+/-0.3 kJ/mol. The pK(a) of DOPE was calculated to shift from 7.7+/-0.1 in the free state to 8.8+/-0.1 in the complex. At physiological ionic strength, proton linkage was not observed upon complex formation and the buffer-independent binding enthalpy was +1.0+/-0.4 kJ/mol. These studies indicate that the intrinsic interaction between 1:1 DOTAP/DOPE and DNA is an entropy-driven process and that the affinities of cationic lipids that are formulated with and without DOPE for DNA are controlled by the positive entropic changes that occur upon complex formation. 相似文献
10.
BackgroundPoor HIV testing uptake by MSM may be attributable to unique challenges that are localized in Southeast Asia.ObjectiveTo characterize MSM who never tested for HIV, to identify correlates of never testing, and to elucidate the perceived barriers to HIV testing.MethodsThe present study used data from the Asian Internet MSM Sex Survey (AIMSS) and restricted the analysis to 4,310 MSM from the ten member countries of the Association of South East Asian Nations (ASEAN).ResultsAmong MSM participants from ASEAN in our sample, 1290 (29.9%) reported having never been tested for HIV, 471 (10.9%) tested for HIV more than 2 years ago, and 2186 (50.7%) reported their last test date was between 6 months and two years ago, with only 363 (8.4%) of these men having been tested in the past 6 months. In multivariable logistic regression, younger MSM (age 15–22 years old [AOR: 4.60, 95% CI: 3.04–6.96]), MSM with lower education (secondary school or lower [AOR: 1.37, 95% CI: 1.03–1.83]), MSM who identify as bisexual or heterosexual (compared to gay-identified) (AOR: 1.94, 95% CI: 1.60–2.35), and MSM who had never used a condom with male partners (AOR: 1.61, 95% CI: 1.32–1.97) had higher odds of never been HIV tested. Main reason for not being tested was a low risk perception of HIV exposure (n = 390, 30.2%).ConclusionCurrent HIV prevention response must not leave MSM “in the dark,” but instead meet them where they are by utilizing the Internet creatively through social media and smart phones. As ASEAN Economic Community (AEC) is quickly becoming a reality, so must there be an equally fast and united response to slowing down the HIV epidemics among MSM in ASEAN. 相似文献