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1.
G. Sandoya R.A. Malvar R. Santiago A. Alvarez P. Revilla A. Butrón 《The Annals of applied biology》2010,156(3):377-386
A maize synthetic population was improved for resistance to the Mediterranean corn borer (MCB, Sesamia nonagrioides) while maintaining yield. The objectives of this research were to investigate whether yield and yield stability of the maize synthetic population named EPS12 were affected by selection for MCB resistance; also to determine which genotypic and environmental covariates could explain the genotype (G), environment (E) and genotype × environment (GE) effects for yield under corn borer infestation. Plants from three cycles of selection and their testcrosses to three inbred testers (A639, B93 and EP42) were evaluated at two locations in 2 years, under MCB and European corn borer infestations. After selection EPS12 was a more stable genotype. Hybrids derived from crosses between B93 and inbreds obtained from the initial cycles of selection could be recommended for cultivation in northern Spain. The yield of crosses between cycles of selection and testers increased when there were fewer days with temperatures >25°C and higher mean maximum temperatures. Differences in yield among these genotypes were mostly explained by resistance to corn borer attack. In general, among EPS12-derived materials, genetic characteristics that contribute to increased grain yield were also responsible for increased abiotic stress tolerance. 相似文献
2.
Agu Laisk Eero Talts Vello Oja Hillar Eichelmann Richard B. Peterson 《Photosynthesis research》2010,103(2):79-95
Fast cyclic electron transport (CET) around photosystem I (PS I) was observed in sunflower (Helianthus annuus L.) leaves under intense far-red light (FRL) of up to 200 μmol quanta m−2 s−1. The electron transport rate (ETR) through PS I was found from the FRL-dark transmittance change at 810 and 950 nm, which
was deconvoluted into redox states and pool sizes of P700, plastocyanin (PC) and cytochrome f (Cyt f). PC and P700 were in
redox equilibrium with K
e = 35 (ΔE
m = 90 mV). PS II ETR was based on O2 evolution. CET [(PS I ETR) − (PS II ETR)] increased to 50–70 μmol e− m−2 s−1 when linear electron transport (LET) under FRL was limited to 5 μmol e− m−2 s−1 in a gas phase containing 20–40 μmol CO2 mol−1 and 20 μmol O2 mol−1. Under these conditions, pulse-saturated fluorescence yield F
m was non-photochemically quenched; however, F
m was similarly quenched when LET was driven by low green or white light, which energetically precluded the possibility for
active CET. We suggest that under FRL, CET is rather not coupled to transmembrane proton translocation than the CET-coupled
protons are short-circuited via proton channels regulated to open at high ΔpH. A kinetic analysis of CET electron donors and
acceptors suggests the CET pathway is that of the reversed Q-cycle: Fd → (FNR) → Cyt cn → Cyt bh → Cyt bl → Rieske FeS → Cyt f → PC → P700 →→ Fd. CET is activated when PQH2 oxidation is opposed by high ΔpH, and ferredoxin (Fd) is reduced due to low availability of e− acceptors. The physiological significance of CET may be photoprotective, as CET may be regarded as a mechanism of energy
dissipation under stress conditions. 相似文献
3.
Bernardo Ordas Rosa A. Malvar Rogelio Santiago German Sandoya Maria C. Romay Ana Butron 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(8):1451-1459
The Mediterranean corn borer or pink stem borer (MCB, Sesamia nonagrioides Lefebvre) causes important yield losses as a consequence of stalk tunneling and direct kernel damage. B73 and Mo17 are the
source of the most commercial valuable maize inbred lines in temperate zones, while the intermated B73 × Mo17 (IBM) population
is an invaluable source for QTL identification. However, no or few experiments have been carried out to detect QTL for corn
borer resistance in the B73 × Mo17 population. The objective of this work was to locate QTL for resistance to stem tunneling
and kernel damage by MCB in the IBM population. We detected a QTL for kernel damage at bin 8.05, although the effect was small
and two QTL for stalk tunneling at bins 1.06 and 9.04 in which the additive effects were 4 cm, approximately. The two QTL
detected for MCB resistance were close to other QTL consistently found for European corn borer (ECB, Ostrinia nubilalis Hübner) resistance, indicating mechanisms of resistance common to both pests or gene clusters controlling resistance to different
plagues. The precise mapping achieved with the IBM population will facilitate the QTL pyramiding and the positional cloning
of the detected QTL. 相似文献
4.
Deyong Sun Yunmei Li Qiao Wang Heng Lv Chengfeng Le Changchun Huang Shaoqi Gong 《Hydrobiologia》2010,644(1):337-349
Light scattering, backscattering, and absorption coefficients of particles were observed at 62 locations in Lake Taihu (China)
in November 2008. A method using a priori knowledge and the measured data was proposed to partition particulate scattering
and absorption into contributions of phytoplankton and non-algal particles. The results showed that phytoplankton weakly contributed
to the particulate scattering and backscattering with the mean b
ph/b
p values usually below 10% and b
bph/b
bt values of 0.3–3.9% in the whole visible light spectrum, and an approximate relationship of b
bt ≈ b
bp ≈ b
bnap was regarded as reasonable in Lake Taihu. In contrast with scattering and backscattering, phytoplankton made more contributions
to the particulate absorption with the mean a
ph/a
p values varying in a wide range of about 20–70%. Both the scattering and absorption spectra of non-algal particles can be
modeled well by corresponding methods. A power function model was used to simulate the scattering spectra, which presented
high predictive accuracies with MAPE values usually below 5% and RMSE values below 1.5 m−1, while the spectral absorption model also performed well with mean S
nap being 0.0052 nm−1 (standard deviation, SD = 0.0010 nm−1). As to the phytoplankton absorption, a quadratic function model used was considered to have a good performance with corresponding
parameters being supported at each wavelength in the spectral range of 400–700 nm. Additionally, two basic bio-optical parameters
were determined, that is, b
nap*(550) = 0.604 m2 g−1 and a
ph*(675) = 0.0288 m2 mg−1. Overall, these results obtained in the present study supply us with new knowledge about optical properties of suspended
particulates in an inland and highly turbid lake (Lake Taihu), which are beneficial to the development of analytical models
of water color remote sensing. 相似文献
5.
R. Ortiz W. W. Wagoire J. Hill S. Chandra S. Madsen O. Stølen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,103(2-3):469-474
Several genotype-by-environment stability measures are in use, but little information exists about their inheritance or genetic
inter-relationships. Among those measures in common use are the linear regression coefficient (b), deviations from regression
(sb), coefficient of determination (R2), coefficient of phenotypic variation (CPV) and, more recently, interaction principal components (IPCA) of the additive-main-effect-and-multiplicative-interaction
(AMMI) model. Because of the factorial structure of the data, the diallel cross is well suited to study these parameters and
their relationship to quantitative traits. For this study a complete diallel cross, derived by mating eight lines from a broad
based bread wheat breeding population, was grown for several growing seasons at two Ugandan locations, one of which was prone
to yellow rust. Stability parameters and grain yield were measured for each cross. CPV had the highest narrow-sense heritability
(h2=0.522) followed by IPCA1 of the AMMI (h2=0.461). Lowest narrow-sense heritabilities were calculated for b and R2 (h2=0.150 and 0.100 respectively). There were high additive genetic correlations (rA) between grain yield and CPV (rA=−0.933), grain yield and IPCA1 (rA=0.707), and grain yield and IPCA2 (rA=0.751). The genetic association between CPV and IPCA1 was also high and negative (rA= −0.934). These results suggest that it may be possible to select simultaneously for high and stable grain yield in this
broad-based bread wheat breeding pool by selecting outyielders that exhibit a low CPV.
Received: 25 July 2000 / Accepted: 7 December 2000 相似文献
6.
Laura Pinilla Rodrigo Torres Claudia Ortiz 《World journal of microbiology & biotechnology》2011,27(11):2521-2528
Two wild strains of Zymomonas mobilis were isolated (named as ML1 and ML2) from sugar cane molasses obtained from different farms of Santander, Colombia. Initially,
selection of the best ethanol-producer strains was carried out using ethanol production parameters obtained with a commercial
strain Z. mobilis DSM 3580. Three isolated strains were cultivated in a culture medium containing yeast extract, peptone, glucose and salts,
at pH 6 and 32°C with stirring rate of 65 rpm during 62 h. The best results of ethanol production were obtained with the native
strain ML1, reaching a maximum ethanol concentration of 79.78 g l−1. ML1 and ML2 strains were identified as Z.
mobilis, according to the morphology, biochemical tests and molecular characterization by PCR of specific DNA sequences from Z. mobilis. Subsequently, the effect of different nitrogen sources on production of ethanol was evaluated. The best results were obtained
using urea at a 0.73 g/l. In this case, maximum concentration of ethanol was 83.81 g l−1, with kinetic parameters of yield of ethanol on biomass (YP/X) = 69.01(g g−1), maximum volumetric productivity of ethanol (Qpmax) = 2.28 (g l−1 h−1), specific productivity of ethanol (qP) = 3.54 (h−1) and specific growth rate (μ) = 0.12 h−1. Finally, we studied the effect of different culture conditions (pH, temperature, stirring, C/N ratio) with a Placket-Burman′s
experimental design. This optimization indicated that the most significant variables were temperature and stirring. In the
best culture conditions a significant increase in all variables of response was achieved, reaching a maximum ethanol concentration
of 93.55 g l−1. 相似文献
7.
A broad regional understanding of tropical forest leaf photosynthesis has long been a goal for tropical forest ecologists,
but it has remained elusive due to difficult canopy access and high species diversity. Here we develop an empirical model
to predict sunlit, light-saturated, tropical leaf photosynthesis using leaf and simulated canopy spectra. To develop this
model, we used partial least squares (PLS) analysis on three tropical forest datasets (159 species), two in Hawaii and one
at the biosphere 2 laboratory (B2L). For each species, we measured light-saturated photosynthesis (A), light and CO2 saturated photosynthesis (A
max), respiration (R), leaf transmittance and reflectance spectra (400–2,500 nm), leaf nitrogen, chlorophyll a and b, carotenoids, and leaf mass per area (LMA). The model best predicted A [r
2
= 0.74, root mean square error (RMSE) = 2.9 μmol m−2 s−1)] followed by R (r
2
= 0.48), and A
max (r
2
= 0.47). We combined leaf reflectance and transmittance with a canopy radiative transfer model to simulate top-of-canopy
reflectance and found that canopy spectra are a better predictor of A (RMSE = 2.5 ± 0.07 μmol m−2 s−1) than are leaf spectra. The results indicate the potential for this technique to be used with high-fidelity imaging spectrometers
to remotely sense tropical forest canopy photosynthesis. 相似文献
8.
Marnie H. Demandt 《Conservation Genetics》2010,11(1):249-255
Genetic drift, together with natural selection and gene flow, affects genetic variation and is the major source of changes
in allele frequencies in small and isolated populations. Temporal shifts in allele frequencies at five polymorphic loci were
used to estimate the amount of genetic drift in an isolated population of perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.). Here, I used the populations from the Biotest basin at Forsmark, Sweden, to investigate genetic diversity between 1977
and 2000, during which time the population can be considered to be totally isolated from other populations. Microsatellite
data reveal stable levels of gene diversity over time for both species. Estimates of genetic differentiation (F
ST) showed a significant divergence between 1977 and 2000 for both perch and roach. A positive correlation between genetic distance
and time was found (Mantel test, perch: r = 0.724, P = 0.0112; roach: r = 0.59, P = 0.036). Estimates of effective population size (N
e) differed with a factor six between two different estimators (NeEstimator and TempoFS) applying the temporal method. Ratios
of N
e/N ranged between 10−2 and 10−3, values normally found in marine species. Despite low N
e the populations have not lost their evolutionary potential due to drift. But two decades of isolation have lead to isolation
by time for populations of perch and roach, respectively. 相似文献
9.
Composition of the mixed culture was varied in combined dark-light fermentation of wheat powder starch in order to improve
hydrogen gas formation rate and yield. Heat-treated anaerobic sludge and pure culture of Clostridium beijerinckii (DSMZ 791
T
) were combined with two different light fermentation bacteria of Rhodobacter sphaeroides (RS-NRRL and RS-RV) in order to select a more suitable mixture resulting in high hydrogen yield and formation rate. A combination
of the anaerobic sludge and RS-NRRL yielded the highest cumulative hydrogen (CHF = 140 ml), the highest yield (0.36 mol H2 mol−1 glucose) and specific hydrogen formation rate (2.5 ml H2 g−1 biomass h−1). During dark fermentation (70 h) hydrogen was produced simultaneously by the dark and light fermentation bacteria using
glucose from hydrolyzed starch. However, only light fermentation bacteria produced hydrogen from VFA’s derived from dark fermentation
after a long adaptation period. 相似文献
10.
Chemical Exchange Saturation Transfer (CEST) is an MRI approach that can indirectly detect exchange broadened protons that
are invisible in traditional NMR spectra. We modified the CEST pulse sequence for use on high-resolution spectrometers and
developed a quantitative approach for measuring exchange rates based upon CEST spectra. This new methodology was applied to
the rapidly exchanging Hδ1 and Hε2 protons of His57 in the catalytic triad of bovine chymotrypsinogen-A (bCT-A). CEST enabled
observation of Hε2 at neutral pH values, and also allowed measurement of solvent exchange rates for His57-Hδ1 and His57-Hε2
across a wide pH range (3–10). Hδ1 exchange was only dependent upon the charge state of the His57 (k
ex,Im+ = 470 s−1, k
ex,Im = 50 s−1), while Hε2 exchange was found to be catalyzed by hydroxide ion and phosphate base (
k\textOH - k_{{{\text{OH}}^{ - } }} = 1.7 × 1010 M−1 s−1,
k\textHPO42 - k_{{{\text{HPO}}_{4}^{2 - } }} = 1.7 × 106 M−1 s−1), reflecting its greater exposure to solute catalysts. Concomitant with the disappearance of the Hε2 signal as the pH was
increased above its pK
a, was the appearance of a novel signal (δ = 12 ppm), which we assigned to Hγ of the nearby Ser195 nucleophile, that is hydrogen bonded to Nε2 of neutral His57. The
chemical shift of Hγ is about 7 ppm downfield from a typical hydroxyl proton, suggesting a highly polarized O–Hγ bond. The
significant alkoxide character of Oγ indicates that Ser195 is preactivated for nucleophilic attack before substrate binding.
CEST should be generally useful for mechanistic investigations of many enzymes with labile protons involved in active site
chemistry. 相似文献
11.
Pilson Choi Yoshiro Mano Atsuko Ishikawa Masashi Odashima Taishi Umezawa Tatsuhito Fujimura Yoshihito Takahata Takao Komatsuda 《Plant biotechnology reports》2010,4(1):23-27
Quantitative trait loci (QTLs) controlling ability of somatic embryogenesis were identified in soybean. A frame map with 204-point
markers was developed using an RI population consisting of 117 F11 lines derived from a cross between cultivar ‘Keburi’ and a weedy soybean ‘Masshokutou Kou 502’. The parents differed greatly
in their abilities of somatic embryogenesis using immature cotyledons as explants. The ability of somatic embryogenesis was
evaluated in five different experiments: the F11 (evaluated in 1998) and F15 (2002) generations cultured on basal media supplemented with 40 mg l−1 2,4-D (2,4-D1998 and 2,4-D2002), F14 (2001) generation on medium with 40 mg l−1 2,4-D and high sucrose concentration [2,4-D2001 (30 g l−1 sucrose)], and the F11 (1998) and F12 (1999) generations on medium with 10 mg l−1 NAA (NAA1998 and NAA1999). The RILs showed wide and continuous variations in each of the five experiments. In the composite
interval mapping analysis, 2 QTLs were found in group 8 (D1b + W, LOD = 5.42, r
2 = 37.5) in the experiment of 2,4-D1998 and in group 6 (C2, LOD = 6.03, r
2 = 26.0) in the experiment of 2,4-D2001 (high concentration sucrose). In both QTLs, alleles of ‘Masshokutou Kou 502’ with
high ability of somatic embryogenesis contributed to the QTLs. For the other three experiments, no QTL was detected in the
criteria of LOD >3.0, suggesting the presence of minor genes. 相似文献
12.
Desert plants have unique strategies for survival and growth to cope with the limited water availability in arid regions.
The stable carbon isotope (δ
13C) provides an integrated measurement of internal plant physiological and external environmental properties affecting photosynthetic
gas exchange and water use efficiency. The δ
13C values of 84 species in the Junggar Basin were categorized into two groups (ranged from −30.1 to −23.3‰ for C3 and −14.9 to −9.9‰ for C4 species, respectively). No life form differences in δ
13C values were detected in C3 (p = 0.78) and C4 plants (p = 0.63). Small differences among life forms were observed in δ
13C values in C4 species with shrubs slightly depleted (−13.3‰) relative to perennials (−13.1‰) and annuals (−12.5‰). These differences suggested
that δ
13C value could not represent a plant functional group classification based on life forms in C4 plants in extremely arid regions. Ephemerals are all using C3 photosynthetic pathway and no significant differences (p = 0.92) in δ
13C values were observed between annuals (−26.5‰) and perennials (−26.4‰). The δ
13C values of Tulipa iliensis (an important ephemeral species distributed widely in the Junggar Basin) among nine natural populations were positively correlated
with leaf (r
2 = 0.46, p = 0.046) and soil (r
2 = 0.67, p = 0.007) total nitrogen content, and negatively correlated with leaf (r
2 = 0.48, p = 0.039) and soil (r
2 = 0.79, p = 0.001) water content. This indicated that the variation in δ
13C values of T. iliensis was probably caused by both water availability associated stomatal openness and nitrogen availability associated photosynthetic
capacity. T. iliensis is very sensitive to water and nitrogen availability in soil. 相似文献
13.
Merja R. Häkkinen Mervi T. Hyvönen Seppo Auriola Robert A. Casero Jr Jouko Vepsäläinen Alex R. Khomutov Leena Alhonen Tuomo A. Keinänen 《Amino acids》2010,38(2):369-381
N-alkylated polyamine analogues have potential as anticancer and antiparasitic drugs. However, their metabolism in the host
has remained incompletely defined thus potentially limiting their utility. Here, we have studied the degradation of three
different spermine analogues N,N′-bis-(3-ethylaminopropyl)butane-1,4-diamine (DESPM), N-(3-benzyl-aminopropyl)-N′-(3-ethylaminopropyl)butane-1,4-diamine (BnEtSPM) and N,N′-bis-(3-benzylaminopropyl)butane-1,4-diamine (DBSPM) and related mono-alkylated derivatives as substrates of recombinant
human polyamine oxidase (APAO) and spermine oxidase (SMO). APAO and SMO metabolized DESPM to EtSPD [K
m(APAO) = 10 μM, k
cat(APAO) = 1.1 s−1 and K
m(SMO) = 28 μM, k
cat(SMO) = 0.8 s−1, respectively], metabolized BnEtSPM to EtSPD [K
m(APAO) = 0.9 μM, k
cat(APAO) = 1.1 s−1 and K
m(SMO) = 51 μM, k
cat(SMO) = 0.4 s−1, respectively], and metabolized DBSPM to BnSPD [K
m(APAO) = 5.4 μM, k
cat(APAO) = 2.0 s−1 and K
m(SMO) = 33 μM, k
cat(SMO) = 0.3 s−1, respectively]. Interestingly, mono-alkylated spermine derivatives were metabolized by APAO and SMO to SPD [EtSPM K
m(APAO) = 16 μM, k
cat(APAO) = 1.5 s−1; K
m(SMO) = 25 μM, k
cat(SMO) = 8.2 s−1; BnSPM K
m(APAO) = 6.0 μM, k
cat(APAO) = 2.8 s−1; K
m(SMO) = 19 μM, k
cat(SMO) = 0.8 s−1, respectively]. Surprisingly, EtSPD [K
m(APAO) = 37 μM, k
cat(APAO) = 0.1 s−1; K
m(SMO) = 48 μM, k
cat(SMO) = 0.05 s−1] and BnSPD [K
m(APAO) = 2.5 μM, k
cat(APAO) = 3.5 s−1; K
m(SMO) = 60 μM, k
cat(SMO) = 0.54 s−1] were metabolized to SPD by both the oxidases. Furthermore, we studied the degradation of DESPM, BnEtSPM or DBSPM in the
DU145 prostate carcinoma cell line. The same major metabolites EtSPD and/or BnSPD were detected both in the culture medium
and intracellularly after 48 h of culture. Moreover, EtSPM and BnSPM were detected from cell samples. Present data shows that
inducible SMO parallel with APAO could play an important role in polyamine based drug action, i.e. degradation of parent drug
and its metabolites, having significant impact on efficiency of these drugs, and hence for the development of novel N-alkylated polyamine analogues. 相似文献
14.
Daria Ezgeta-Balić Melita Peharda Christopher A. Richardson Marina Kuzmanić Nedo Vrgoč Igor Isajlović 《Helgoland Marine Research》2011,65(4):457-465
The age, growth, and population structure of the smooth clam Callista chione were determined from samples collected by hydraulic dredge and SCUBA at four locations in the eastern Adriatic during 2007
and 2008. The age of 436 clam shells was determined from internal growth lines present in shell sections, and the timing of
growth line formation was ascertained from monthly collections of clams to occur between August and September when sea water
temperatures were maximal. In addition, age of 30 older individuals was verified with acetate peels of polished and etched
shell sections. Differences were apparent in the age structure and growth rates of clams collected from the four locations
studied. Von Bertalanffy growth (VBG) curves obtained for clams from these locations were L
t
= 72.4 (1−e−0.25(t − 2.68)) (Rab Island), L
t
= 74.5 (1−e−0.15(t + 0.57)) (Pag Bay), L
t
= 79.3 (1−e−0.34(t − 0.97)) (Cetina estuary), and L
t
= 82.5 (1−e−0.11(t + 2.88)) (Kaštela Bay). The age of the clams ranged between 3 and 44 years; median clam ages were similar at three of the four locations
(14, 12, and 12 years, respectively), but was significantly lower in the Cetina estuary (4 years). The VBG growth constants
recorded from clams were within the range of values obtained for this species by previous authors. The observed local differences
in population structure indicate different levels of exploitation and illustrate the need to establish long-term strategies
for a sustainable exploitation of smooth clams in the Croatian Adriatic. 相似文献
15.
The scattering spectrum properties of highly turbid and eutrophic inland case 2 water from Taihu Lake were studied during
three cruises from 2006 to 2007. The scattering [b
p(λ)] and backscattering [b
bp(λ)] coefficients and the backscattering probability (B) for Taihu Lake were found to show a clear spectral dependence, and this dependence was well simulated by a power-law function.
This dependence, however, became weak when algae dominated the sample points. The mean values of the power-law index for b
p(λ), v, in Oct 2006, Mar 2007 and Nov 2007 were −0.6712, −0.8129 and −0.7600, respectively. To interpret the spectral characteristics
and mechanisms of b
p(λ) and b
bp(λ), water samples were collected simultaneously for the biogeochemical characterization of suspended particles. The average
values of the specific scattering coefficients for total suspended matter, inorganic suspended matter (ISPM) and organic suspended
matter (OSPM) were 0.634 (550 nm), 1.057 (532 nm), and 0.396 g m−2 (532 nm), respectively. The power-law index of b
bp(λ) (Y) was significantly related to ISPM/OSPM and b
bp(532 nm), but only weakly related to the particle size distribution index. The mean (spatial and wavelength) values of B in Oct 2006, Mar 2007, and Nov 2007 were 0.0108, 0.0138, and 0.0125, respectively. B decreases with increasing ISPM concentration because of the large contribution of ISPM to b
b(λ) and the strong restraint on b
bp(λ) caused by the multi-scattering effect under high-turbidity conditions. 相似文献
16.
We investigated the effects of limiting (1.96 × 10−9 mol l−1 total Cu, corresponding to pCu 14.8; where pCu = −log [Cu2+]) and toxic Cu concentrations up to 8.0 × 10−5 mol l−1 total Cu (equivalent to pCu 9.5) on growth rates and photosynthetic activity of exponentially grown Phaeocystis cordata, using batch and semi-continuous cultures. With pulse amplitude modulated (PAM) fluorometry, we determined the photochemical
response of P. cordata to the various Cu levels, and showed contrasting results for the batch and semi-continuous cultures. Although maximum photosystem
II (PSII) quantum yield (ΦM) was optimal and constant in the semi-continuous P. cordata, the batch cultures showed a significant decrease in ΦM with culture age (0–72 h). The EC50 for the batch cultures was higher (2.0 × 10−10 mol l−1, pCu9.7), than that for the semi-continuous cultures (6.3 × 10−11 mol l−1, pCu10.2). The semi-continuous cultures exhibited a systematic and linear decrease in ΦM as Cu levels increased (for [Cu2+] < 1.0 × 10−12 mol l−1, pCu12.0), however, no effect of high Cu was observed on their operational PSII quantum yield (Φ′M). Similarly, semi-continuous cultures exhibited a significant decrease in ΦM, but not in Φ′M, because of low-Cu levels. Thus, Cu toxicity and Cu limitation damage the PSII reaction centers, but not the processes downstream
of PSII. Quenching mechanisms (NPQ and Q
n) were lower under high Cu relative to the controls, suggesting that toxic Cu impairs photo-protective mechanisms. PAM fluorometry
is a sensitive tool for detecting minor physiological variations. However, culturing techniques (batch vs. semi-continuous)
and sampling time might account for literature discrepancies on the effects of Cu on PSII. Semi-continuous culturing might
be the most adequate technique to investigate Cu effects on PSII photochemistry. 相似文献
17.
Jayati Roy Choudhury Lu Rao Ulrich Bierbach 《Journal of biological inorganic chemistry》2011,16(3):373-380
A restriction enzyme cleavage inhibition assay was designed to determine the rates of DNA platination by four non-cross-linking
platinum–acridine agents represented by the formula [Pt(am2)LCl](NO3)2, where am is a diamine nonleaving group and L is an acridine derived from the intercalator 1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea
(ACRAMTU). The formation of monofunctional adducts in the target sequence 5′-CGA was studied in a 40-base-pair probe containing
the EcoRI restriction site GAATTC. The time dependence of endonuclease inhibition was quantitatively analyzed by polyacrylamide gel
electrophoresis. The formation of monoadducts is approximately 3 times faster with double-stranded DNA than with simple nucleic
acid fragments. Compound 1 (am2 is ethane-1,2-diamine, L is ACRAMTU) reacts with a first-order rate constant of k
obs = 1.4 ± 0.37 × 10−4 s−1 (t
1/2 = 83 ± 22 min). Replacement of the thiourea group in ACRAMTU with an amidine group (compound 2) accelerates the rate by fourfold (k
obs = 5.7 ± 0.58 × 10−4 s−1, t
1/2 = 21 ± 2 min), and introduction of a propane-1,3-diamine nonleaving group results in a 1.5-fold enhancement in reactivity
(compound 3, k
obs = 2.1 ± 0.40 × 10−4 s−1, t
1/2 = 55 ± 10 min) compared with the prototype. Derivative 4, containing a 4,9-disubstituted acridine threading intercalator, was the least reactive compound in the series (k
obs = 1.1 ± 0.40 × 10−4 s−1, t
1/2 = 104 ± 38 min). The data suggest a correlation may exist between the binding rates and the biological activity of the compounds.
Potential pharmacological advantages of rapid formation of cytotoxic monofunctional adducts over the common purine–purine
cross-links are discussed. 相似文献
18.
The growth performance of malolactic fermenting bacteria Oenococcus oeni NCIMB 11648 and Lactobacillus brevis X2 was assessed in continuous culture. O. oeni grew at a dilution rate range of 0.007 to 0.052 h−1 in a mixture of 5:6 (g l−1) of glucose/fructose at an optimal pH of 4.5, and L. brevis X2 grew at 0.010 to 0.089 h−1 in 10 g l−1 glucose at an optimal pH of 5.5 in a simple and safe medium. The cell dry weight, substrate uptake and product formation
were monitored, as well as growth kinetics, yield parameters and fermentation balances were also evaluated under pH control
conditions. A comparison of growth characteristics of two strains was made, and this showed significantly different performance.
O. oeni has lower maximum specific growth rate (μmax=0.073 h−1), lower maximum cell productivity (Q
x
max=17.6 mg cell l−1 h−1), lower maximum biomass yield (Y
x/s
max=7.93 g cell mol−1 sugar) and higher maintenance coefficient (m
s=0.45 mmol−1 sugar g−1 cell h−1) as compared with L. brevis X2 (μmax=0.110 h−1; Q
x
max=93.2 g−1 cell mol−1 glucose; Y
x/s
max=22.3 g cell mol−1 glucose; m
s=0.21 mmol−1 glucose g−1 cell h−1). These data suggest a possible more productive strategy for their combined use in maturation of cider and wine. 相似文献
19.
Jackellynne Fernanda Fernandes Jailza Freitas Yago Bruno Silveira Nunes Mariana Barros Aranha Rafael Santos Lobato Marina Bezerra Figueiredo 《Zeitschrift fur angewandte Ichthyologie》2020,36(4):539-541
The length to weight ratio (LWR) was used to estimate populations of four fish species sampled on the Amazon coast of the state of Maranhão, Brazil. The fishes were sampled in 2018 and 2019 by artisanal coastal fishing, using gillnets (0.20–0.60 mm). The parameters a and b of the equation WT = a LTb were estimated. The obtained LWRs were WT = 0.06LT2.93, (r2) = .989 for Oligoplites saliens; WT = 0.061LT2.57, (r2) = .982 for Peprilus crenulatus; WT = 0.014LT2.80, (r2) = .985 for Bagre bagre; and WT = 0.035LT3.21, (r2) = .981 for Nebris microps. 相似文献
20.
Toxic at low concentrations, phenol is one of the most common organic pollutants in air and water. In this work, phenol biodegradation
was studied in extreme conditions (80°C, pH = 3.2) in a 2.7 l bioreactor with the thermoacidophilic archaeon Sulfolobus solfataricus 98/2. The strain was first acclimatized to phenol on a mixture of glucose (2000 mg l−1) and phenol (94 mg l−1) at a constant dissolved oxygen concentration of 1.5 mg l−1. After a short lag-phase, only glucose was consumed. Phenol degradation then began while glucose was still present in the
reactor. When glucose was exhausted, phenol was used for respiration and then for biomass build-up. After several batch runs
(phenol < 365 mg l−1), specific growth rate (μX) was 0.034 ± 0.001 h−1, specific phenol degradation rate (qP) was 57.5 ± 2 mg g−1 h−1, biomass yield (YX/P) was 52.2 ± 1.1 g mol−1, and oxygen yield factor
( \textY\textX/\textO 2 ) \left( {{\text{Y}}_{{{\text{X}}/{\text{O}}_{ 2} }} } \right) was 9.2 ± 0.2 g mol−1. A carbon recovery close to 100% suggested that phenol was exclusively transformed into biomass (35%) and CO2 (65%). Molar phenol oxidation constant
( \textY\textO 2 /\textP ) \left( {{\text{Y}}_{{{\text{O}}_{ 2} /{\text{P}}}} } \right) was calculated from stoichiometry of phenol oxidation and introducing experimental biomass and CO2 conversion yields on phenol, leading to values varying between 4.78 and 5.22 mol mol−1. Respiratory quotient was about 0.84 mol mol−1, very close to theoretical value (0.87 mol mol−1). Carbon dioxide production, oxygen demand and redox potential, monitored on-line, were good indicators of growth, substrate
consumption and exhaustion, and can therefore be usefully employed for industrial phenol bioremediation in extreme environments. 相似文献