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1.
Mammalian metallothioneins (
\textM7\textIIMTs {\text{M}}_7^{\text{IIMTs}} ) show a clustered arrangement of the metal ions and a nonregular protein structure. The solution structures of Cd3-thiolate cluster containing β-domain of mouse β-MT-1 and rat β-MT-2 show high structural similarities, but widely differing
structure dynamics. Molecular dynamics simulations revealed a substantially increased number of
\textNH - \textSg {\text{NH - }}{{\text{S}}^\gamma } hydrogen bonds in β-MT-2, features likely responsible for the increased stability of the Cd3-thiolate cluster and the enfolding protein domain. Alterations in the
\textNH - \textSg {\text{NH - }}{{\text{S}}^\gamma } hydrogen-bonding network may provide a rationale for the differences in dynamic properties encountered in the β-domains of
MT-1, -2, and -3 isoforms, believed to be essential for their different biological function. 相似文献
2.
3.
Pseudomonas aeruginosa phosphorylcholine phosphatase (PchP) catalyzes the hydrolysis of phosphorylcholine, which is produced by the action of hemolytic
phospholipase C on phosphatidylcholine or sphyngomielin, to generate choline and inorganic phosphate. Among divalent cations,
its activity is dependent on Mg2+ or Zn2+. Mg2+ produced identical activation at pH 5.0 and 7.4, but Zn2+ was an activator at pH 5.0 and became an inhibitor at pH 7.4. At this higher pH, very low concentrations of Zn2+ inhibited enzymatic activity even in the presence of saturating Mg2+ concentrations. Considering experimental and theoretical physicochemical calculations performed by different authors, we
conclude that at pH 5.0, Mg2+ and Zn2+ are hexacoordinated in an octahedral arrangement in the PchP active site. At pH 7.4, Mg2+ conserves the octahedral coordination maintaining enzymatic activity. The inhibition produced by Zn2+ at 7.4 is interpreted as a change from octahedral to tetrahedral coordination geometry which is produced by hydrolysis of
the
[ \textZn 2+ \textL 2 - 1 \textL 20 ( \textH 2 \textO ) 2 ] \left[ {{\text{Zn}}^{ 2+ } {\text{L}}_{ 2}^{ - 1} {\text{L}}_{ 2}^{0} \left( {{\text{H}}_{ 2} {\text{O}}} \right)_{ 2} } \right] complex. 相似文献
4.
Total height, diameter, index volume, stem straightness, apical dominance, and survival were assessed at 8 years from seed
in an open-pollinated progeny test of 36 families of European chestnut (Castanea sativa Miller) established at two sites in the Atlantic area of Galicia, Spain. Iterative spatial analysis was applied to eliminate
the effect of the spatial dependence in the original data and to estimate accurately genetic parameters for evaluating the
potential for selection of the measured trees. Spatial analysis was very beneficial for growth traits and survival, but less
so if at all for form traits. Estimated individual heritabilities ranged from moderate to high for growth traits ([^(h)]i2 = 0.29 - 0.42 \widehat{h}_i^2 = 0.29 - 0.42 ) and stem straightness ([^(h)]i2 = 0.24 - 0.42 \widehat{h}_i^2 = 0.{24} - 0.{42} ). High coefficients of additive genetic variance were obtained for volume (
[^(\textC)]\textV\textA = 36.5 - 41.5% \widehat{\text{C}}{{\text{V}}_{\text{A}}} = {36}.{5} - {41}.{5}\% ) and straightness (
[^(\textC)]\textV\textA = 44.26 - 53.84% \widehat{\text{C}}{{\text{V}}_{\text{A}}} = {44}.{26} - {53}.{84}\% ). Phenotypic and estimated genetic correlations between growth traits were very high, and correlations between sites indicated
that there was no important family × site interaction. No adverse correlations between traits were evident. The results indicate
the ample potential for selection in the current progeny trial, where responses to within-family and combined selection for
growth traits may be high. Accordingly, three selection scenarios were addressed with the aim to initiate the selection of
individuals for implementing the Forest Breeding Plan of Galicia for European chestnut. 相似文献
5.
Described here is a set of three-dimensional (3D) NMR experiments that rely on CACA-TOCSY magnetization transfer via the weak
3 \textJ\textCa\textCa ^{ 3} {\text{J}}_{{{\text{C}}\alpha {\text{C}}\alpha }} coupling. These pulse sequences, which resemble recently described 13C detected CACA-TOCSY (Takeuchi et al. 2010) experiments, are recorded in 1H2O, and use 1H excitation and detection. These experiments require alternate 13C-12C labeling together with perdeuteration, which allows utilizing the small
3 \textJ\textCa\textCa ^{ 3} {\text{J}}_{{{\text{C}}\alpha {\text{C}}\alpha }} scalar coupling that is otherwise masked by the stronger 1JCC couplings in uniformly 13C labeled samples. These new experiments provide a unique assignment ladder-mark that yields bidirectional supra-sequential
information and can readily straddle proline residues. Unlike the conventional HNCA experiment, which contains only sequential
information to the
1 3 \textCa ^{ 1 3} {\text{C}}^{\alpha } of the preceding residue, the 3D hnCA-TOCSY-caNH experiment can yield sequential correlations to alpha carbons in positions
i−1, i + 1 and i−2. Furthermore, the 3D hNca-TOCSY-caNH and Hnca-TOCSY-caNH experiments, which share the same magnetization pathway but use
a different chemical shift encoding, directly couple the 15N-1H spin pair of residue i to adjacent amide protons and nitrogens at positions i−2, i−1, i + 1 and i + 2, respectively. These new experimental features make protein backbone assignments more robust by reducing the degeneracy problem
associated with the conventional 3D NMR experiments. 相似文献
6.
B. Culik A. J. Woakes D. Adelung R. P. Wilson N. R. Coria H. J. Spairani 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1990,160(1):61-70
Summary The energy requirements of Adélie penguin (Pygoscelis adeliae) chicks were analysed with respect to body mass (W, 0.145–3.35 kg, n=36) and various forms of activity (lying, standing, minor activity, locomotion, walking on a treadmill). Direct respirometry was used to measure O2 consumption (
) and CO2 production. Heart rate (HR, bpm) was recorded from the ECG obtained by both externally attached electrodes and implantable HR-transmitters. The parameters measured were not affected by hand-rearing of the chicks or by implanting transmitters. HR measured in the laboratory and in the field were comparable. Oxygen uptake ranged from
in lying chicks to
at maximal activity, RQ=0.76. Metabolic rate in small wild chicks (0.14–0.38 kg) was not affected by time of day, nor was their feeding frequency in the colony (Dec 20–21). Regressions of HR on
were highly significant (p< 0.0001) in transmitter implanted chicks (n=4), and two relationships are proposed for the pooled data, one for minor activities (
), and one for walking (
). Oxygen consumption, mass of the chick (2–3 kg), and duration of walking (T, s) were related as
, whereas mass-specific O2 consumption was related to walking speed (S, m·s-1) as
.Abbreviations
bpm
beats per minute
-
D
distance walked (m)
-
ECG
electrocardiogram
-
HR
heart rate (bpm)
-
ns
number of steps
-
RQ
respiratory quotient
-
S
walking speed (m·s-1)
-
T
time walked (s)
-
W
body mass (kg) 相似文献
7.
Chul-Woong Cho Thi Phuong Thuy Pham Sok Kim Young-Ran Kim You-Chul Jeon Yeoung-Sang Yun 《Journal of applied phycology》2009,21(6):683-689
The acute toxicities of common organic solvents (e.g., methanol, ethanol, isopropanol, acetone, acetonitrile, and dimethylformamide) were evaluated using a biosensor based on microalgal photosynthesis measurement. The biosensor was air-tight, with no headspace, preventing volatile organic toxicants from escaping into the environment as well as partitioning from the aqueous phase into the headspace until equilibrium was reached. Both the incubating and exposure times were set at 10 min. It was observed that only 2 h was needed to obtain complete dose-related inhibition of photosynthetic activity. The results showed that all the tested organic solvents inhibited algal photosynthesis with EC50 ranging between 589 and 2,570 mM. The inhibition of these solvents was in the order: isopropanol > acetone > acetonitrile > ethanol > dimethylformamide > methanol. The quantitative structure-activity relationship (QSAR) between toxicity data and partition coefficient of the examined compounds could be modeled as follows: ${\text{log}}_{{10}} {\text{EC}}_{{50}} \;{\left( {\mu {\text{M}}} \right)} = - 0.6428\;{\text{log}}\;P + 5.76\;{\left( {{\text{R}}^{2} \approx 0.88} \right)}The acute toxicities of common organic solvents (e.g., methanol, ethanol, isopropanol, acetone, acetonitrile, and dimethylformamide)
were evaluated using a biosensor based on microalgal photosynthesis measurement. The biosensor was air-tight, with no headspace,
preventing volatile organic toxicants from escaping into the environment as well as partitioning from the aqueous phase into
the headspace until equilibrium was reached. Both the incubating and exposure times were set at 10 min. It was observed that
only 2 h was needed to obtain complete dose-related inhibition of photosynthetic activity. The results showed that all the
tested organic solvents inhibited algal photosynthesis with EC50 ranging between 589 and 2,570 mM. The inhibition of these solvents was in the order: isopropanol > acetone > acetonitrile
> ethanol > dimethylformamide > methanol. The quantitative structure-activity relationship (QSAR) between toxicity data and
partition coefficient of the examined compounds could be modeled as follows:
\textlog10 \textEC50 ( m\textM ) = - 0.6428 \textlog P + 5.76 ( \textR2 ? 0.88 ){\text{log}}_{{10}} {\text{EC}}_{{50}} \;{\left( {\mu {\text{M}}} \right)} = - 0.6428\;{\text{log}}\;P + 5.76\;{\left( {{\text{R}}^{2} \approx 0.88} \right)}. This indicates that the photosynthetic activity of the microalga Pseudokirchneriella subcapitata is highly dependent on the hydrophobicity of these commonly used organic solvents. 相似文献
8.
We measured the self-diffusion coefficients of water in a Nafion membrane and two sulfonated polyethersulfone (SPES) membranes
with varying ion-exchange capacities (IEC) in terms of relative humidity using the pulse field gradient NMR (PFG-NMR) technique.
The self-diffusion coefficients were plotted against the number of water molecules per sulfonic acid group, λ, and compare these values with the results of molecular dynamics (MD) simulations. Classical MD simulations for all membranes
were carried out using a consistent force field at λ = 3, 6, 9, 12, and 15. The dynamic properties of water (H2O) and hydronium (H3O+) on a molecular level were estimated as self-diffusion coefficients and residence times around a sulfonate group (
\textSO3- {\text{SO}}_3^{-} ). The diffusion coefficients of H2O and H3O+ followed the order, Nafion > SPES with IEC = 1.4 > SPES with IEC = 1.0 > SPES with IEC = 0.75, which agreed with the experimental
data. The residence time distribution of H2O around
\textSO3- {\text{SO}}_3^{-} in Nafion was in the range of 1–6 ps, whereas H2O in the SPES exhibited a residence time of greater than 20 ps. 相似文献
9.
10.
Mollica A Pinnen F Feliciani F Stefanucci A Lucente G Davis P Porreca F Ma SW Lai J Hruby VJ 《Amino acids》2011,40(5):1503-1511
We report the synthesis and the biological evaluation of two new analogues of the potent dimeric opioid peptide biphalin.
The performed modification is based on the replacement of two key structural elements of the native biphalin, namely: the
hydrazine bridge which joins the two palindromic moieties and the phenylalanine residues at the 4,4′ positions of the backbone.
The new analogues 9 and 10 contain 1,2-phenylenediamine and piperazine, respectively, in place of the hydrazidic linker and p-fluoro-l-phenylalanine residues at 4 and 4′ positions. Binding values are:
K\textim = 0.51 \textnM K_{\text{i}}^{\mu } = 0.51\,{\text{nM}} and
K\textid = 12.8 \textnM K_{\text{i}}^{\delta } = 12.8\,{\text{nM}} for compound 9,
K\textim = 0.09 \textnM K_{\text{i}}^{\mu } = 0.09\,{\text{nM}} and
K\textid = 0.11 \textnM K_{\text{i}}^{\delta } = 0.11\,{\text{nM}} for analogue 10. 相似文献
11.
Eng-Seng Chan Peh-Phong Lee Pogaku Ravindra Kamatan Krishnaiah Wan-Ping Voo 《Applied microbiology and biotechnology》2010,86(1):385-391
The aim of this work was to develop a standard quantitative method to measure the acid tolerance of probiotic cells when exposed
to a simulated gastric fluid. Three model strains of different cell concentrations were exposed to a standard simulated gastric
fluid of fixed volume. The fluid pH ranged from pH 1.5 to 2.5. In general, the death kinetics followed an exponential trend.
The overall death constant, k
d, for all strains was found to be in a power relationship with the pH value and the initial cell concentration, and it can
be expressed as
k\textd\text = k\textAII( \textp\textH - \text9.0N0 - 0.\text19 ) {k_{\text{d}}}{\text{ = }}{k_{\text{AII}}}\left( {{\text{p}}{{\text{H}}^{ - {\text{9}}.0}}{N_0}^{ - 0.{\text{19}}}} \right) 相似文献
12.
Acute hyperammonemia (HA) induced oxidative stress in the brain is considered to play critical roles in the neuropathology
of end stage hepatic encephalopathy (HE). Moderate grade HA led minimal/moderate type HE is more common in the patients with
chronic liver failure. However, implication of oxygen free radical (
\textO 2 - {\text{O}}_{ 2}^{ - } ) based oxidative mechanisms remain to be defined during moderate grade HA. This article describes profiles of all the antioxidant
enzymes Vis a Vis status of oxidative stress/damage in the brain slices exposed to 0.1–1 mM ammonia, reported to exist in
the brain of animals with chronic liver failure and in liver cirrhotic patients. Superoxide dismutase catalyzes the first
step of antioxidant mechanism and, with concerted activity of catalase, neutralizes
\textO 2 - {\text{O}}_{ 2}^{ - } produced in the cells. Both these enzymes remained unchanged up to 0.2–0.3 mM ammonia, however, with significant increments
(P < 0.01–0.001) in the brain slices exposed to 0.5–1 mM ammonia. This was consistent with the similar pattern of production
of reactive oxygen species in the brain slices. However, level of lipid peroxidation remained unchanged throughout the ammonia
treatment. Synchronized activities of glutathione peroxidase and glutathione reductase regulate the level of glutathione to
maintain reducing equivalents in the cells. The activities of both these enzymes also increased significantly in the brain
slices exposed to 0.5–1 mM ammonia with concomitant increments in GSH/GSSG ratio and in the levels of total and protein bound
thiol. The findings suggest resistance of brain cells from ammonia induced oxidative damage during moderate grade HA due to
concordant activations of antioxidant enzymes. 相似文献
13.
Physiological characterization of ‘stay green’ wheat cultivars during the grain filling stage under field growing conditions 总被引:1,自引:0,他引:1
Junbo Chen Yun Liang Xueyun Hu Xianxiang Wang Feiquan Tan Huaiqiong Zhang Zhenglong Ren Peigao Luo 《Acta Physiologiae Plantarum》2010,32(5):875-882
Rye (Secale cereale L.) chromosome arm 1RS could delay leaf senescence, and change in H2O2 content is a useful index for weighing the ability to delay the senescence. Two wheat cultivars, Chuannong12 (CN12) and Chuannong
18 (CN18), harboring the wheat–rye 1BL/1RS translocated chromosome were investigated for H2O2 change and physiological index after flowering under field conditions, and MY11, the agronomical parent of both CN12 and
CN18, was used as the control. A combined change in the peak value of CdSe/ZnS quantum dot (QD) fluorescence and morphological
observation indicated that the H2O2 contents in CN12 and CN18 were generally lower than that in MY11. They both had higher values for net photosynthetic rate
(P
n), stomatal conductance (G
s),
F\textv /F\textm¢ F_{\text{v}} /F_{\text{m}}^{\prime }
F\textv¢ /F\textm¢ F_{\text{v}}^{\prime } /F_{\text{m}}^{\prime } , and photochemical quenching of PSII (qP) than MY11 only in the late measurement stage. Some small differences were also
observed, such as CN12 and CN18 wheat cultivars having higher and longer photosynthetic competence than MY11 during the grain
filling stage, which perhaps resulted from a mechanism for removing oxidative species, especially H2O2. 相似文献
14.
Hydrogenases are metalloenzymes that catalyze the reversible reaction
\textH2 \leftrightarrows 2\textH + + 2\texte - {\text{H}}_{2} \leftrightarrows 2{\text{H}}^{ + } + 2{\text{e}}^{ - } , being potentially useful in H2 production or oxidation. [NiFeSe] hydrogenases are a particularly interesting subgroup of the [NiFe] class that exhibit tolerance
to O2 inhibition and produce more H2 than standard [NiFe] hydrogenases. However, the molecular determinants responsible for these properties remain unknown. Hydrophobic
pathways for H2 diffusion have been identified in [NiFe] hydrogenases, as have proton transfer pathways, but they have never been studied
in [NiFeSe] hydrogenases. Our aim was, for the first time, to characterize the H2 and proton pathways in a [NiFeSe] hydrogenase and compare them with those in a standard [NiFe] hydrogenase. We performed
molecular dynamics simulations of H2 diffusion in the [NiFeSe] hydrogenase from Desulfomicrobium baculatum and extended previous simulations of the [NiFe] hydrogenase from Desulfovibrio gigas (Teixeira et al. in Biophys J 91:2035–2045, 2006). The comparison showed that H2 density near the active site is much higher in [NiFeSe] hydrogenase, which appears to have an alternative route for the access
of H2 to the active site. We have also determined a possible proton transfer pathway in the [NiFeSe] hydrogenase from D. baculatum using continuum electrostatics and Monte Carlo simulation and compared it with the proton pathway we found in the [NiFe]
hydrogenase from D. gigas (Teixeira et al. in Proteins 70:1010–1022, 2008). The residues constituting both proton transfer pathways are considerably different, although in the same region of the
protein. These results support the hypothesis that some of the special properties of [NiFeSe] hydrogenases could be related
to differences in the H2 and proton pathways. 相似文献
15.
Kazuya Yoshimura Nobuhiro Zaitsu Yuta Sekimura Bunkei Matsushita Takehiko Fukushima Akio Imai 《Hydrobiologia》2012,691(1):157-169
The chlorophyll a-specific absorption coefficient ( a\textph* ( l) a_{\text{ph}}^{*} \left( \lambda \right) ) in a highly eutrophic lake can show characteristics distinct from that in the ocean due to the differences in the structure and composition of phytoplankton. In this study, investigated the variation of a\textph* ( l) a_{\text{ph}}^{*} \left( \lambda \right) in Lake Kasumigaura, a highly eutrophic lake in Japan, in association with the package effect and the effect of accessory pigments, and carried out the parameterization of a\textph* ( l) a_{\text{ph}}^{*} \left( \lambda \right) . Although a\textph* ( l) a_{\text{ph}}^{*} \left( \lambda \right) did not vary spatially, it did show significant temporal variation, with a particularly high value after spring-bloom. This high a\textph* ( l) a_{\text{ph}}^{*} \left( \lambda \right) in spring was attributed to a lower package effect and a higher proportion of carotenoid than the other samples. Although the value of a\textph* ( l) a_{\text{ph}}^{*} \left( \lambda \right) was correlated with the concentration of chlorophyll-a (Chl-a), the correlation coefficient was lower than those reported in the ocean. Some lake-water samples showed variations of the package effect and the effect of accessory pigments that were independent of the concentration of Chl-a, and these independent variations resulted in the weak correlation between a\textph* ( l) a_{\text{ph}}^{*} \left( \lambda \right) and the concentration of Chl-a. Together, these results suggest that the factors controlling a\textph* ( l) a_{\text{ph}}^{*} \left( \lambda \right) in highly eutrophic lakes are distinct from that in ocean samples. 相似文献
16.
Although nitrate is a macronutrient and can serve as good nitrogen source for many species of phytoplankton, high nitrate
concentrations do not benefit the growth of phytoplankton. We hypothesise that algae cultured under high nitrate concentrations
can accumulate intracellular nitrite, which is produced by nitrate reductase (NR) and can inhibit the growth of algae. To
assess the validity of this hypothesis, Microcystis aeruginosa was grown under different nitrate concentrations from 3.57 to 21.43 mM in low CO2 and high CO2 conditions for 15 days. We observed that, with increasing nitrate concentrations, the intracellular nitrite concentrations
of the alga increased and the growth rates and photosynthesis declined. When grown under high CO2 conditions, M. aeruginosa showed lower intracellular nitrite concentrations and higher growth rates and
\textP\textm\textchla {\text{P}}_{\text{m}}^{{\text{chl}}a} ,
\textR\textd\textchla {\text{R}}_{\text{d}}^{{\text{chl}}a} , αchla
than under low CO2 conditions. These results suggest that the accumulation of intracellular nitrite could be the cause of inhibition of algal
growth under high nitrate concentrations. 相似文献
17.
Leonard G. Forgan Malcolm E. Forster 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(5):715-729
We present evidence that oxygen consumption
(V\textO2 ) (V_{{{\text{O}}_{2} }} ) is oxygen partial pressure
(P\textO2 ) (P_{{{\text{O}}_{2} }} ) dependent in striated muscles and
P\textO2 P_{{{\text{O}}_{2} }} -independent in the vasculature in representatives of three craniate taxa: two teleost fish, a hagfish and a rat. Blood vessel
V\textO2 V_{{{\text{O}}_{2} }} displayed varying degrees of independence in a
P\textO2 P_{{{\text{O}}_{2} }} range of 15–95 mmHg, while
V\textO2 V_{{{\text{O}}_{2} }} by striated muscle tissue slices from all species related linearly to
P\textO2 P_{{{\text{O}}_{2} }} between 0 and 125 mmHg, despite
V\textO2 V_{{{\text{O}}_{2} }} rates varying greatly between species and muscle type. In salmon red muscle, lactate concentrations fell in slices incubated
at a
P\textO2 P_{{{\text{O}}_{2} }} of either 30 or 100 mmHg, suggesting aerobic rather than anaerobic metabolism. Consistent with this finding, potential energy,
a proxy of ATP turnover, was
P\textO2 P_{{{\text{O}}_{2} }} -dependent. Our data suggest that the reduction in
V\textO2 V_{{{\text{O}}_{2} }} with falling
P\textO2 P_{{{\text{O}}_{2} }} results in a decrease in ATP demand, suggesting that the hypoxic signal is sensed and cellular changes effected. Viability
and diffusion limitation of the preparations were investigated using salmon cardiac and skeletal muscles. Following the initial
P\textO2 P_{{{\text{O}}_{2} }} depletion, reoxygenation of the Ringer bathing salmon cardiac muscle resulted in
V\textO2 \texts V_{{{\text{O}}_{2} }} {\text{s}} that was unchanged from the first run.
V\textO2 V_{{{\text{O}}_{2} }} increased in all muscles uncoupled with p-trifluoromethoxylphenyl-hydrazone (FCCP) and 2,4-dinitrophenol (DNP). Mitochondrial succinate dehydrogenase activity, quantified
by reduction of 3-(4,5-dimethylthiazol)-2,5-diphenyl-2H-tetrazolium bromide (MTT) to formazan, was constant over the course of the experiment. These three findings indicate that
the tissues remained viable over time and ruled out diffusion-limitation as a constraint on
V\textO2 V_{{{\text{O}}_{2} }} . 相似文献
18.
Juliana Vitória Messias Bittencourt Alexandre Magno Sebbenn 《Tree Genetics & Genomes》2009,5(4):573-582
Araucaria angustifolia is an endangered tropical/subtropical coniferous of great interest for conservation due its economical, ecological, and social
value. Only 3% of original Araucaria forests remain, which are generally confined to small forest fragments. Forest fragmentation can have serious consequences
on genetic process in tree population, affecting long-term fitness and adaptability. To investigate the effects of forest
fragmentation on genetic diversity and the structure of A. angustifolia populations, the genetic diversity of eight microsatellite loci was compared in four small fragmented populations (<22 ha),
four tree groups (five to 11 trees) occurring in pastures and in three plots in a large continuous population. The clearest
effect of fragmentation was the loss of rare alleles (p ≤ 0.05) in fragmented populations (19.4% to 47.2%) and intermediate frequency (0.05 < p ≤ 0.25) and rare alleles (p ≤ 0.05) in tree groups (19% to 86.1%) in comparison to continuous populations. Fragmented populations have significant higher
fixation index (
[^(F)]\textIS = 0.121 \widehat{F}_{\text{IS}} = 0.121 , P < 0.05) than continuous populations (
[^(F)]\textIS = 0.083 \widehat{F}_{\text{IS}} = 0.083 , P < 0.05). High genetic differentiation was detected among tree groups (
[^(G)]\textST¢ = 0.258 \widehat{G}_{{{\text{ST}}}}^{\prime } = 0.258 , P < 0.01) and low among fragments (
[^(G)]\textST¢ = 0.031 \widehat{G}_{{{\text{ST}}}}^{\prime } = 0.031 , P < 0.05) and continuous populations (
[^(G)]\textST¢ = 0.026 \widehat{G}_{{{\text{ST}}}}^{\prime } = 0.026 , P < 0.05), showing a significant bottleneck effect in tree groups. Evidence that forest fragments have experienced a recent
bottleneck was confirmed in at least two studied fragments. The implications of the results for conservation of the fragmented
A. angustifolia populations are discussed. 相似文献
19.
Summary A set of three-dimensional triple-resonance experiments is described which provide
,
,
and
coupling constants. The pulse sequences generate E.COSY-like multiplet patterns and comprise a magnetization transfer from
the amide proton to the α-proton or vice versa via the directly bound heteronuclei. For residues with the 1Hα spin resonating close to the H2O signal, a modified HNCA experiment can be employed to measure the vicinal 1HN,1Hα couplings. Ambiguities associated with the conversion of
values into ϕ-angle constraints for protein structure determination can be resolved with the knowledge of the heteronuclear
3J-couplings. In favourable cases, stereospecific assignments of glycine α-protons can be obtained by employing the experiments
described here in combination with NOE data. The methods are applied to flavodoxin from Desulfovibrio vulgaris. 相似文献
20.
Beth L. Young David A. S. Rosen Martin Haulena Allyson G. Hindle Andrew W. Trites 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2011,181(1):105-116
The ability to use heart rate (fh) to predict oxygen consumption rates (
[(V)\dot]\textO2 \dot{V}_{{{\text{O}}_{2} }} ) in Steller sea lions and other pinnipeds has been investigated in fasting animals. However, it is unknown whether established
fh:
[(V)\dot]\textO2 \dot{V}_{{{\text{O}}_{2} }} relationships hold under more complex physiological situations, such as when animals are feeding or digesting. We assessed
whether fh could accurately predict
[(V)\dot]\textO2 \dot{V}_{{{\text{O}}_{2} }} in trained Steller sea lions while fasting and after being fed. Using linear mixed-effects models, we derived unique equations
to describe the fh:
[(V)\dot]\textO2 \dot{V}_{{{\text{O}}_{2} }} relationship for fasted sea lions resting on land and in water. Feeding did not significantly change the fh:
[(V)\dot]\textO2 \dot{V}_{{{\text{O}}_{2} }} relationship on land. However, Steller sea lions in water displayed a different fh:
[(V)\dot]\textO2 \dot{V}_{{{\text{O}}_{2} }} relationship after consuming a 4-kg meal compared with the fasting condition. Incorporating comparable published fh:
[(V)\dot]\textO2 \dot{V}_{{{\text{O}}_{2} }} data from Steller sea lions showed a distinct effect of feeding after a 6-kg meal. Ultimately, our study illustrated that
both feeding and physical environment are statistically relevant when deriving
[(V)\dot]\textO2 \dot{V}_{{{\text{O}}_{2} }} from telemetered fh, but that only environment affects the practical ability to predict metabolism from fh. Updating current
bioenergetic models with data gathered using these predictive fh:
[(V)\dot]\textO2 \dot{V}_{{{\text{O}}_{2} }} equations will yield more accurate estimates of metabolic rates of free-ranging Steller sea lions under a variety of physiological,
behavioral, and environmental states. 相似文献
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