共查询到20条相似文献,搜索用时 15 毫秒
1.
S. Nakamura S. Asakawa N. Ohmido K. Fukui N. Shimizu S. Kawasaki 《Molecular & general genetics : MGG》1997,254(6):611-620
We constructed a rice Bacterial Artificial Chromosome (BAC) library from green leaf protoplasts of the cultivar Shimokita
harboring the rice blast resistance gene Pi-ta. The average insert size of 155 kb and the library size of seven genome equivalents make it one of the most comprehensive
BAC libraries available, and larger than many plant YAC libraries. The library clones were plated on seven high density membranes
of microplate size, enabling efficient colony identification in colony hybridization experiments. Seven percent of clones
carried chloroplast DNA. By probing with markers close to the blast resistance genes Pi-ta
2
(closely linked to Pi-ta) and Pi-b, respectively located in the centromeric region of chromosome 12 and near the telomeric end of chromosome 2, on average 2.2 ± 1.3
and 8.0 ± 2.6 BAC clones/marker were isolated. Differences in chromosomal structures may contribute to this wide variation
in yield. A contig of about 800 kb, consisting of 19 clones, was constructed in the Pi-ta
2
region. This region had a high frequency of repetitive sequences. To circumvent this difficulty, we devised a “two-step walking”
method. The contig spanned a 300 kb region between markers located at 0 cM and 0.3 cM from Pi-ta
2
. The ratio of physical to genetic distances (> 1,000 kb/cM) was more than three times larger than the average of rice (300
kb/cM). The low recombination rate and high frequency of repetitive sequences may also be related to the near centromeric
character of this region. Fluorescent in situ hybridization (FISH) with a BAC clone from the Pi-b region yielded very clear signals on the long arm of chromosome 2, while a clone from the Pi-ta
2
region showed various cross-hybridizing signals near the centromeric regions of all chromosomes.
Received: 14 August 1996 / Accepted: 2 December 1996 相似文献
2.
RFLP and RAPD markers linked to the rosy leaf curling aphid resistance gene (Sd1) in apple 总被引:10,自引:0,他引:10
P. Roche F. H. Alston C. Maliepaard K. M. Evans R. Vrielink F. Dunemann T. Markussen S. Tartarini L. M. Brown C. Ryder G. J. King 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(3-4):528-533
Sd
1 is a dominant gene for resistance to biotypes 1 and 2 of the rosy leaf curling aphid, Dysaphis devecta Wlk., which can cause economic damage to apple trees. This report describes the identification of three RFLP and four RAPD
markers linked to Sd
1 in a cross between the D. devecta susceptible variety ‘Prima’ (sd
1
sd
1) and the resistant variety ‘Fiesta’ (Sd
1
sd
1). Potted trees were artificially infested in the glasshouse, and the ratio of resistant:susceptible plants supported the
hypothesis that the resistance was under the control of a single dominant gene. The position of the gene was mapped to a single
locus on a ‘Fiesta’ chromosome, within 2 cM of three tightly linked RFLP markers (MC064a, 2B12a and MC029b); the four RAPD
markers were located further away (between 13 and 46 cM). This is the first report of molecular markers for an aphid resistance
gene in tree fruit crops. The potential application of these markers in a marker-assisted resistance breeding programme is
discussed.
Received: 1 July 1996/Accepted: 23 August 1996 相似文献
3.
W. E. Van de Weg 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(8):1092-1096
Phytophthora fragariae var. fragariae is the causal agent of red stele (red core) root rot in strawberry (Fragaria spp.). The inheritance of resistance to one isolate of this fungus was studied in 12 segregating populations of F.×ananassa derived from crosses between four resistant cultivars (‘Climax’, ‘Redgauntlet’, ‘Siletz’, and ‘Sparkle’) and three susceptible
cultivars (‘Blakemore’, ‘Glasa’, and ‘Senga’ Sengana’). The analysis clearly supports the hypothesis of a single segregating
dominant resistance gene. It is proposed that this gene be designated Rpf2.
Received 12 November 1996 / Accepted: 22 November 1996 相似文献
4.
Michael J. Webster Timothy P. Scheett Matthew R. Doyle Matthew Branz 《European journal of applied physiology and occupational physiology》1997,75(6):520-524
The purpose of this study was to investigate the effect of a thiamin derivative, thiamin tetrahydrofurfuryl disulfide (TTFD),
on oxygen uptake (˙VO2), lactate accumulation and cycling performance during exercise to exhaustion. Using a randomized, double-blind, cross-over
design with a 10-day washout between trials, 14 subjects ingested either 1 g · day−1 of TTFD or a placebo (PL) for 4 days. On day 3, subjects performed a progressive exercise test to exhaustion on a cycle ergometer
for the determination of ˙VO2submax, ˙VO2peak, lactate concentration ([La− ]), lactate threshold (ThLa) and heart rate ( f
c). On day 4, subjects performed a maximal 2000-m time trial on a cycle ergometer. A one-way analysis of variance (ANOVA) with
repeated measures was used to determine significant differences between trials. There were no significant differences detected
between trials for serial measures of ˙VO2submax, [La−] or f
c. Likewise, ˙VO2peak [PL 4.06 (0.19) TTFD 4.12 (0.19) l · min−1, P = 0.83], ThLa [PL 2.47 (0.17), TTFD 2.43 (0.16) l · min−1, P = 0.86] and 2000-m performance time [PL 204.5 (5.5), TTFD 200.9 (4.3) s, P = 0.61] were not significantly different between trials. The results of this study suggest that thiamin derivative supplementation
does not influence high-intensity exercise performance.
Accepted: 19 December 1996 相似文献
5.
F. Vear L. Gentzbittel J. Philippon S. Mouzeyar E. Mestries P. Roeckel-Drevet D. Tourvieille de Labrouhe P. Nicolas 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(4):584-589
These studies were undertaken to determine whether downy mildew resistance genes in sunflower were independent as first reported,
or linked as suggested by more recent hypotheses. The segregations for downy mildew reaction of 111 F3 progenies from a cross between a susceptible line and a line with Pl2 were used to locate this gene on the sunflower consensus RFLP linkage map. It was shown that Pl2 was linked to the same RFLP markers on linkage group 1 as Pl1 and Pl6, mapped earlier, and at a very similar distance. The F3 progenies showed exactly the same segregation patterns when tested with race 1 and race D. One hundred and fifty four progenies
from a cross between a susceptible line and HA335, containing Pl6 (considered as giving resistance to all Plasmopara halstedii races), were tested with the five French downy mildew races, 1, A, B, C and D. Two progenies were observed to show segregation
for races 1 and D, while appearing homozygous-resistant to races A , B and C. Tests on F4 progenies confirmed this separation of resistances with fixation of susceptibility to races 1 and D and resistance to races
A, B and C. It is concluded that the Pl6 gene is not a “strong” gene, giving resistance to all downy mildew races, but rather a cluster of genes, each providing resistance
to one, or a few, downy mildew races. The genes giving resistance to races 1 and D, on one hand, and to races A, B and C,
on the other hand, must be very closely linked, with about 0.6 cM between the two groups.
Received: 23 December 1996 / Accepted: 18 April 1997 相似文献
6.
R. A. Young M. Melotto R. O. Nodari J. D. Kelly 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(1):87-94
Two independently assorting dominant genes conditioning resistance to bean anthracnose were identified in an F2 population derived from the highly resistant bean differential cultivar, ‘G 2333’. One gene was allelic to the Co-4 gene in the differential cultivar ‘TO’ and was named Co-4
2
, whereas the second gene was assigned the temporary name Co-7 until a complete characterization with other known resistance genes can be conducted. Two RAPD markers linked to the Co-4
2
allele were identified. One RAPD, OAS13950, co-segregated with no recombinants in two segregating populations of 143 F2 individuals, whereas the second RAPD, OAL9740, mapped at 3.9 cM from the Co-4
2
allele. Two 24-mer SCAR primers (SAS13), developed from the OAS13950 RAPD marker, were dominant and polymorphic, similar to the original RAPD, and supported the tight linkage between the marker(s)
and the Co-4
2
allele. The markers were present in germplasm with known resistance alleles at the Co-4 locus. The presence of the markers in two other differential cultivars not previously characterized and in four navy bean
cultivars suggests the existence of a gene family for anthracnose resistance at or near the Co-4 locus. Since the Co-7 gene was present only in germplasm which also possessed the Co-4
2
and Co-5 genes, the SAS13 markers were used in combination with standard inoculation techniques to identify F3 lines in which the Co-7 gene was homozygous and the Co-4
2
allele was absent. A similar strategy of marker-assisted dissection is proposed to identify resistant lines in which the
Co-5 gene is absent and the Co-7 gene is present by selecting against the OAB3450 marker, which has been shown previously to be linked to the Co-5 gene. These genes cannot be distinguished using traditional screening methods since all current races of the pathogen virulent
to the Co-5 gene are avirulent to the Co-4
2
and Co-7 genes. We describe the use of molecular markers tightly linked to resistance genes to facilitate the identification of an
uncharacterized resistance gene for which no discriminating race of the pathogen is known.
Received: 22 March 1997 / Accepted: 15 July 1997 相似文献
7.
Light response characteristics of a morphologically diverse group of southern hemisphere conifers as measured by chlorophyll fluorescence 总被引:5,自引:0,他引:5
Unlike northern hemisphere conifer families, the southern family, Podocarpaceae, produces a great variety of foliage forms
ranging from functionally broad-, to needle-leaved. The production of broad photosynthetic surfaces in podocarps has been
linked qualitatively to low-light-environments, and we undertook to assess the validity of this assumption by measuring the
light response of a morphologically diverse group of podocarps. The light response, as apparent photochemical electron transport
rate (ETR), was measured by modulated fluorescence in ten species of this family and six associated species (including five
Cupressaceae and one functionally needle-leaved angiosperm) all grown under identical glasshouse conditions. In all species,
ETR was found to increase as light intensity increased, reaching a peak value (ETRmax) at saturating quantum flux (PPFDsat), and decreasing thereafter. ETRmax ranged from 217 μmol electrons · m−2 · s−1 at a PPFDsat of 1725 μmol photons · m−2 · s−1 in Actinostrobus acuminatus to an ETR of 60 μmol electrons · m−2 · s−1 at a PPFDsat of 745 μmol electrons · m−2 · s−1 in Podocarpus dispermis. Good correlations were observed between ETRmax and both PPFDsat and maximum assimilation rate measured by gas-exchange analysis. The effective quantum yield at light saturation remained
constant in all species with an average value of 0.278 ± 0.0035 determined for all 16 species. Differences in the shapes of
light response curves were related to differences in the response of non-photochemical quenching (q
n), with q
n saturating faster in species with low PPFDsat. Amongst the species of Podocarpaceae, the log of average shoot width was well correlated with PPFDsat, wider leaves saturating at lower light intensities. This suggests that broadly flattened shoots in the Podocarpaceae are
an adaptation to low light intensity.
Received: 15 April 1996 / Accepted: 30 September 1996 相似文献
8.
Tiecheng Qiao Robert Witkowski Robin Henderson G. McLendon 《Journal of biological inorganic chemistry》1996,1(5):432-438
The kinetics of methemoglobin reduction by cytochrome b
5 has been studied by stopped-flow and saturation transfer NMR. A forward rate constant k
f = 2.44×104 M–1 s–1 and a reverse rate constant k
b = 540 M–1s–1 have been observed at 10 mm, pH 6.20, 25 °C. The ratio k
f/k
b = k
eq = 43.6 is in good agreement with the equilibrium constant calculated from the electrochemical potential between cyt b
5 and methemoglobin. A bimolecular collisional mechanism is proposed for the electron transfer from cyt b
5 to methemoglobin based on the kinetic data analysis. The dependence of the rate constants on ionic strengths supports such
collisional mechanism. It is also found that the reaction rate strongly depends on the conformations of methemoglobin.
Received: 20 February 1996 / Accepted: 4 June 1996 相似文献
9.
J. T. Kemp M. K. Balasubramanian K. L. Gould 《Molecular & general genetics : MGG》1997,254(2):127-138
The organization of the actin cytoskeleton plays an integral role in cell morphogenesis of all eukaryotes. We have isolated
a temperature-sensitive mutant in Schizosaccharomyces pombe, wat1-1, in which acting patches are delocalized, resulting in an elliptically shaped cell phenotype. Molecular cloning and DNA sequencing
of wat1
+ showed that the gene encodes a 314 residue protein containing WD-40 repeats. Cells lacking wat1
+ are slow growing but viable at 25° C and temperature-sensitive for growth above 33° C. At restrictive temperature, wat1-d strains are phenotypically indistinguishable from wat1-1. When combined with a deletion for the wat1
+ gene, cdc mutants failed to elongate at restrictive temperature and exhibited alterations in actin patch localization. This
analysis suggests that wat1
+ is required directly or indirectly for polarized cell growth in S. pombe. Wat1p and a functional, epitope-tagged, version of Wat1p can be overproduced without inducing alterations in cell morphology.
Received: 18 September 1996 / Accepted: 22 October 1996 相似文献
10.
Identification of molecular markers linked to quantitative trait loci for soybean resistance to corn earworm 总被引:7,自引:0,他引:7
B. G. Rector J. N. All W. A. Parrott H. R. Boerma 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(6-7):786-790
One hundred and thirty nine restriction fragment length polymorphisms (RFLPs) were used to construct a soybean (Glycine max L. Merr.) genetic linkage map and to identify quantitative trait loci (QTLs) associated with resistance to corn earworm (Helicoverpa zea Boddie) in a population of 103 F2-derived lines from a cross of ‘Cobb’ (susceptible) and PI229358 (resistant). The genetic linkage map consisted of 128 markers
which converged onto 30 linkage groups covering approximately 1325 cM. There were 11 unlinked markers. The F2-derived lines and the two parents were grown in the field under a plastic mesh cage near Athens, Ga., in 1995. The plants
were artificially infested with corn earworm and evaluated for the amount of defoliation. Using interval-mapping analysis
for linked markers and single-factor analysis of variance (ANOVA), markers were tested for an association with resistance.
One major and two minor QTLs for resistance were identified in this population. The PI229358 allele contributed insect resistance
at all three QTLs. The major QTL is linked to the RFLP marker A584 on linkage group (LG) ‘M’ of the USDA/Iowa State University
public soybean genetic map. It accounts for 37% of the total variation for resistance in this cross. The minor QTLs are linked
to the RFLP markers R249 (LG ‘H’) and Bng047 (LG ‘D1’). These markers explain 16% and 10% of variation, respectively. The
heritability (h2) for resistance was estimated as 64% in this population.
Received: 15 October 1997 / Accepted: 4 November 1997 相似文献
11.
Influence of stand structure on carbon-13 of vegetation, soils, and canopy air within deciduous and evergreen forests in Utah, United States 总被引:15,自引:0,他引:15
Carbon isotope ratios (δ13C) were studied in evergreen and deciduous forest ecosystems in semi-arid Utah (Pinus contorta, Populus tremuloides, Acer negundo and Acer grandidentatum). Measurements were taken in four to five stands of each forest ecosystem differing in overstory leaf area index (LAI) during
two consecutive growing seasons. The δ13Cleaf (and carbon isotope discrimination) of understory vegetation in the evergreen stands (LAI 1.5–2.2) did not differ among canopies
with increasing LAI, whereas understory in the deciduous stands (LAI 1.5–4.5) exhibited strongly decreasing δ13Cleaf values (increasing carbon isotope discrimination) with increasing LAI. The δ13C values of needles and leaves at the top of the canopy were relatively constant over the entire LAI range, indicating no
change in intrinsic water-use efficiency with overstory LAI. In all canopies, δ13Cleaf decreased with decreasing height above the forest floor, primarily due to physiological changes affecting c
i/c
a (> 60%) and to a minor extent due to δ13C of canopy air (< 40%). This intra-canopy depletion of δ13Cleaf was lowest in the open stand (1‰) and greatest in the denser stands (4.5‰). Although overstory δ13Cleaf did not change with canopy LAI, δ13C of soil organic carbon increased with increasing LAI in Pinus contorta and Populus tremuloides ecosystems. In addition, δ13C of decomposing organic carbon became increasingly enriched over time (by 1.7–2.9‰) for all deciduous and evergreen dry temperate
forests. The δ13Ccanopy of CO2 in canopy air varied temporally and spatially in all forest stands. Vertical canopy gradients of δ13Ccanopy, and [CO2]canopy were larger in the deciduous Populus tremuloides than in the evergreen Pinu contorta stands of similar LAI. In a very wet and cool year, ecosystem discrimination (Δe) was similar for both deciduous Populus tremulodies (18.0 ± 0.7‰) and evergreen Pinus contorta (18.3 ± 0.9‰) stands. Gradients of δ13Ccanopy and [CO2]canopy were larger in denser Acer spp. stands than those in the open stand. However, 13C enrichment above and photosynthetic draw-down of [CO2]canopy below tropospheric baseline values were larger in the open than in the dense stands, due to the presence of a vigorous understory
vegetation. Seasonal patterns of the relationship δ13Ccanopy versus 1/[CO2]canopy were strongly influenced by precipitation and air temperature during the growing season. Estimates of Δe for Acer spp. did not show a significant effect of stand structure, and averaged 16.8 ± 0.5‰ in 1933 and 17.4 ± 0.7‰ in 1994. However,
Δe varied seasonally with small fluctuations for the open stand (2‰), but more pronounced changes for the dense stand (5‰).
Received: 15 April 1996 / Accepted: 19 October 1996 相似文献
12.
Theodore J. Angelopoulos Robert J. Robertson F. L. Goss Allan Utter 《European journal of applied physiology and occupational physiology》1997,75(2):132-135
Eight fit men [maximum oxygen consumption (O2max) 64.6 (1.9) ml · kg−1 · min−1, aged 28.3 (1.7) years (SE in parentheses) were studied during two treadmill exercise trials to determine the effect of endogenous
opioids on insulin and glucagon immunoreactivity during intense exercise (80% O2max). A double-blind experimental design was used with subjects undertaking the two exercise trials in counterbalanced order.
Exercise trials were 20 min in duration and were conducted 7 days apart. One exercise trial was undertaken following administration
of naloxone (N; 1.2 mg; 3 ml) and the other after receiving a placebo (P; 0.9% NaCl saline; 3 ml). Prior to each experimental
trial a flexible catheter was placed into an antecubital vein and baseline blood samples were collected. Immediately after,
each subject received either a N or P bolus injection. Blood samples were also collected after 20 min of continuous exercise
(running). Glucagon was higher (P < 0.05), while insulin was lower (P < 0.05), during exercise compared with pre-exercise values in both trials. However, glucagon was higher (P < 0.05) in the P than in the N exercise trial [141.4 (8.3) ng · l−1 vs 127.2 (7.6) ng · l−1]. There were no differences in insulin during exercise between the P and N trials [50.2 (4.3) pmol · l−1 vs 43.8 (5) pmol · l−1]. These data suggest that endogenous opioids may augment the glucagon response during intense exercise.
Accepted: 15 June 1996 相似文献
13.
R. Turcotte L. Kiteala J. E. Marcotte H. Perrault 《European journal of applied physiology and occupational physiology》1997,75(5):425-430
The purpose of this investigation was to examine if exercise-induced arterial oxyhemoglobin desaturation selectively observed
in highly trained endurance athletes could be related to differences in the pulmonary diffusing capacity (D
L) measured during exercise. The D
L of 24 male endurance athletes was measured using a 3-s breath-hold carbon monoxide procedure (to give D
LCO) at rest as well as during cycling at 60% and 90% of these previously determined O2max. Oxyhemoglobin saturation (S
aO2%) was monitored throughout both exercise protocols using an Ohmeda Biox II oximeter. Exercise-induced oxyhemoglobin desaturation
(DS) (S
aO2% < 91% at O2max) was observed in 13 subjects [88.2 (0.6)%] but not in the other 11 nondesaturation subjects [NDS: 92.9 (0.4)%] (P ≤ 0.05), although O2max was not significantly different between the groups [DS: 4.34 (0.65) l / min vs NDS: 4.1 (0.49) l / min]. At rest, no differences
in either D
LCO [m1 CO · mmHg−1 · min−1: 41.7 (1.7) (DS) vs 41.1 (1.8) (NDS)], D
LCO /
A
[8.2 (0.4) (DS) vs 7.3 (0.9) (NDS)], MVV [l / min: 196.0 (10.4) (DS) vs 182.0 (9.9) (NDS)] or FEV1/FVC [86.3 (2.2) (DS) vs 82.9 (4.7) (NDS)] were found between groups (P ≥ 0.05). However,
E /O2 at O2max was lower in the DS group [33.0 (1.1)] compared to the NDS group [36.8 (1.5)] (P ≤ 0.05). Exercise D
LCO (m1 CO · mmHg−1 · min−1 ) was not different between groups at either 60% O2max [DS: 55.1 (1.4) vs NDS: 57.2 (2.1)] or at 90% O2max [DS: 61.0 (1.8) vs NDS: 61.4 (2.9)]. A significant relationship (r = 0.698) was calculated to occur between S
aO2% and
E /O2 during maximal exercise. The present findings indicate that the exercise-induced oxyhemoglobin desaturation seen during submaximal
and near-maximal exercise is not related to differences in D
L, although during maximal exercise S
aO2 may be limited by a relatively lower exercise ventilation.
Accepted: 25 September 1996 相似文献
14.
Interseasonal comparison of CO2 concentrations, isotopic composition, and carbon dynamics in an Amazonian rainforest (French Guiana) 总被引:2,自引:0,他引:2
Canopy CO2 concentrations in a tropical rainforest in French Guiana were measured continuously for 5 days during the 1994 dry season
and the 1995 wet season. Carbon dioxide concentrations ([CO2]) throughout the canopy (0.02–38 m) showed a distinct daily pattern, were well-stratified and decreased with increasing height
into the canopy. During both seasons, daytime [CO2] in the upper and middle canopy decreased on average 7–10 μmol mol−1 below tropospheric baseline values measured at Barbados. Within the main part of the canopy (≥ 0.7 m), [CO2] did not differ between the wet and dry seasons. In contrast, [CO2] below 0.7 m were generally higher during the dry season, resulting in larger [CO2] gradients. Supporting this observation, soil CO2 efflux was on average higher during the dry season than during the wet season, either due to diffusive limitations and/or
to oxygen deficiency of root and microbial respiration. Soil respiration rates decreased by 40% after strong rain events,
resulting in a rapid decrease in canopy [CO2] immediately above the forest floor of about 50␣μmol mol−1. Temporal and spatial variations in [CO2]canopy were reflected in changes of δ13Ccanopy and δ18Ocanopy values. Tight relationships were observed between δ13C and δ18O of canopy CO2 during both seasons (r
2 > 0.86). The most depleted δ13Ccanopy and δ18Ocanopy values were measured immediately above the forest floor (δ13C = −16.4‰; δ18O = 39.1‰ SMOW). Gradients in the isotope ratios of CO2 between the top of the canopy and the forest floor ranged between 2.0‰ and 6.3‰ for δ13C, and between 1.0‰ and 3.5‰ for δ18O. The δ13Cleaf and calculated c
i/c
a of foliage at three different positions were similar for the dry and wet seasons indicating that the canopy maintained a
constant ratio of photosynthesis to stomatal conductance. About 20% of the differences in δ13Cleaf within the canopy was accounted for by source air effects, the remaining 80% must be due to changes in c
i/c
a. Plotting 1/[CO2] vs. the corresponding δ13C ratios resulted in very tight, linear relationships (r
2 = 0.99), with no significant differences between the two seasons, suggesting negligible seasonal variability in turbulent
mixing relative to ecosystem gas exchange. The intercepts of these relationships that should be indicative of the δ13C of respired sources were close to the measured δ13C of soil respired CO2 and to the δ13C of litter and soil organic matter. Estimates of carbon isotope discrimination of the entire ecosystem, Δe, were calculated as 20.3‰ during the dry season and as 20.5‰ during the wet season.
Received: 3 March 1996 / Accepted: 19 October 1996 相似文献
15.
C. Immoos Michael G. Hill Donita Sanders James A. Fee Claire E. Slutter John H. Richards Harry B. Gray 《Journal of biological inorganic chemistry》1996,1(6):529-531
The electrochemistry of a water-soluble fragment from the CuA domain of Thermus thermophilus cytochrome ba
3
has been investigated. At 25 °C, CuA exhibits a reversible reduction at a pyridine-4-aldehydesemicarbazone-modified gold electrode (0.1 M Tris, pH 8) with E° = 0.24 V vs NHE. Thermodynamic parameters for the [Cu(Cys)2Cu]+/0 electrode reaction were determined by variable-temperature electrochemistry (ΔS°rc = –5.4(12) eu, ΔS° = –21.0(12) eu, ΔH° = –11.9(4) kcal/mol;ΔG° = –5.6 (11) kcal/mol). The relatively small reaction entropy is consistent with a low reorganization energy for [Cu(Cys)2Cu]+/0 electron transfer. An irreversible oxidation of [Cu(Cys)2Cu]+ at 1 V vs NHE confirms that the CuII:CuII state of CuA is significantly destabilized relative to the CuII state of analogous blue-copper proteins.
Received: 3 June 1996 / Accepted: 26 August 1996 相似文献
16.
Development of RAPD and SCAR markers linked to the Russian wheat aphid resistance gene Dn2 in wheat 总被引:5,自引:0,他引:5
A. A. Myburg M. Cawood B. D. Wingfield A.-M. Botha 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(8):1162-1169
RAPD (random amplified polymorphic DNA) analysis was used to identify molecular markers linked to the Dn2 gene conferring resistance to the Russian wheat aphid (Diuraphis noxia Mordvilko). A set of near-isogenic lines (NILs) was screened with 300 RAPD primers for polymorphisms linked to the Dn2 gene. A total of 2700 RAPD loci were screened for linkage to the resistance locus. Four polymorphic RAPD fragments, two in
coupling phase and two in repulsion phase, were identified as putative RAPD markers for the Dn2 gene. Segregation analysis of these markers in an F2 population segregating for the resistance gene revealed that all four markers were closely linked to the Dn2 locus. Linkage distances ranged from 3.3 cM to 4.4 cM. Southern analysis of the RAPD products using the cloned RAPD markers
as probes confirmed the homology of the RAPD amplification products. The coupling-phase marker OPB10880c and the repulsion-phase marker OPN1400r were converted to sequence characterized amplified region (SCAR) markers. SCAR analysis of the F2 population and other resistant and susceptible South African wheat cultivars corroborated the observed linkage of the RAPD
markers to the Dn2 resistance locus. These markers will be useful for marker-assisted selection of the Dn2 gene for resistance breeding and gene pyramiding.
Received: 1 July 1997 / Accepted: 20 October 1997 相似文献
17.
D. Thomas A. D. Scot R. Barbey M. Padula S. Boiteux 《Molecular & general genetics : MGG》1997,254(2):171-178
The OGG1 gene of Saccharomyces cerevisiae encodes a DNA glycosylase that excises 7,8-dihydro-8-oxoguanine (8-OxoG) and 2,6-diamino-4-hydroxy-5-N-methylformamidopyrimidine. To investigate the biological role of the OGG1 gene, mutants were constructed by partial deletion of the coding sequence and insertion of marker genes, yielding ogg1::TRP1 and ogg1::URA3 mutant strains. The disruption of the OGG1 gene does not compromise the viability of haploid cells, therefore it is not an essential gene. The capacity to repair 8-OxoG
has been measured in cell-free extracts of wild-type and ogg1 strains using a 34mer DNA fragment containing a single 8-OxoG residue paired with a cytosine (8-OxoG/C) as a substrate. Cell-free
extracts of the wild-type strain efficiently cleave the 8-OxoG-containing strand of the 8-OxoG/C duplex. In contrast, cell-free
extracts of the Ogg1-deficient strain have no detectable activity that can cleave the 8-OxoG/C duplex. The biological properties
of the ogg1 mutant have also been investigated. The results show that the ogg1 disruptant is not hypersensitive to DNA-damaging agents such as ultraviolet light at 254 nm, hydrogen peroxide or methyl methanesulfonate.
However, the ogg1 mutant exhibits a mutator phenotype. When compared to those of a wild-type strain, the frequencies of mutation to canavanine
resistance (CanR) and reversion to Lys+ are sevenfold and tenfold higher for the ogg1 mutant strain, respectively. Moreover, using a specific tester system, we show that the Ogg1-deficient strain displays a
50-fold increase in spontaneously occurring G · C→T · A transversions compared to the wild-type strain. The five other base
substitution events are not affected by the disruption of the OGG1 gene. These results strongly suggest that endogeneous reactive oxygen species cause DNA damage and that the excision of 8-OxoG
catalyzed by the Ogg1 protein contributes to the maintenance of genetic stability in S. cerevisiae.
Received: 6 September 1996 / Accepted: 22 October 1996 相似文献
18.
Isabelle Sendowski Gustave Savourey Yves Besnard Jacques Bittel 《European journal of applied physiology and occupational physiology》1997,75(6):471-477
To study the physiological responses induced by immersing in cold water various areas of the upper limb, 20 subjects immersed
either the index finger (T1), hand (T2) or forearm and hand (T3) for 30 min in 5°C water followed by a 15-min recovery period.
Skin temperature of the index finger, skin blood flow (Qsk) measured by laser Doppler flowmetry, as well as heart rate (HR) and mean arterial blood pressure (ˉBPa) were all monitored during the test. Cutaneous vascular conductance (CVC) was calculated as Qsk / ˉBPa. Cold induced vasodilatation (CIVD) indices were calculated from index finger skin temperature and CVC time courses. The
results showed that no differences in temperature, CVC or cardiovascular changes were observed between T2 and T3. During T1,
CIVD appeared earlier compared to T2 and T3 [5.90 (SEM 0.32) min in T1 vs 7.95 (SEM 0.86) min in T2 and 9.26 (SEM 0.78) min
in T3, P < 0.01]. The HR was unchanged in T1 whereas it increased significantly at the beginning of T2 and T3 [+13 (SEM 2) beats · min−1 in T2 and +15 (SEM 3) beats · min−1 in T3, P < 0.01] and then decreased at the end of the immersion [−12 (SEM 3) beats · min−1 in T2, and −15 (SEM 3) beats · min−1 in T3, P < 0.01]. Moreover, ˉBPaincreased at the beginning of T1 but was lower than in T2 and T3 [+9.3 (SEM 2.5) mmHg in T1, P < 0.05; +20.6 (SEM 2.6) mmHg and 26.5 (SEM 2.8) mmHg in T2 and T3, respectively, P < 0.01]. The rewarming during recovery was faster and higher in T1 compared to T2 and T3. These results showed that general
and local physiological responses observed during an upper limb cold water test differed according to the area immersed. Index
finger cooling led to earlier and faster CIVD without significant cardiovascular changes, whereas hand or forearm immersion
led to a delayed and slower CIVD with a bradycardia at the end of the test.
Accepted: 26 November 1996 相似文献
19.
The vertical profile of stable carbon isotope ratios (δ13C) of leaves was analyzed for 13 tree species in a cool-temperate deciduous forest in Japan. The vertical distribution of
long-term averaged δ13C in atmospheric CO2 (δa) was estimated from δ13C of dry matter from NADP-malic enzyme type C4 plant (Zea mays L. var. saccharata Sturt.) grown at a tower in the forest for 32␣days, assuming constant Δ value (3.3‰) in Z. mays against height. The δa value obtained from δ13C in Z.␣mays was lowest at the forest floor (−9.30 ± 0.03‰), increased with height, and was almost constant above 10␣m (−7.14 ± 0.14‰).
Then leaf Δ values for the tree species were calculated from tree leaf δ13 C andδa. Mean leaf Δ values for the three tall deciduous species (Fraxinus mandshurica, Ulmus davidiana, and Alnus hirsuta) were significantly different among three height levels in the forest: 23.1 ± 0.7‰ at the forest floor (understory), 21.4 ± 0.5‰
in lower canopy, and 20.5 ± 0.3‰ in upper canopy. The true difference in tree leaf Δ among the forest height levels might
be even greater, because Δ in Z. mays probably increased with shading by up to ∼‰. The difference in tree leaf Δ among the forest height levels would be mainly
due to decreasing intercellular CO2 (C
i) with the increase in irradiance. Potential assimilation rate for the three tree species probably increased with height,
since leaf nitrogen content on an area basis for these species also increased with height. However, the increase in stomatal
conductance for these tree species would fail to meet the increase in potential assimilation rate, which might lead to increasing
the degree of stomatal limitation in photosynthesis with height.
Received: 30 September 1995 / Accepted: 25 October 1996 相似文献
20.
Suzette R. Cooke Stewart R. Petersen H. Arthur Quinney 《European journal of applied physiology and occupational physiology》1997,75(6):512-519
Phosphorus magnetic resonance spectroscopy (31P-MRS) was used to investigate the influence of maximal aerobic power (˙VO
2max) on the recovery of human calf muscle from high-intensity exercise. The (˙VOO2max) of 21 males was measured during treadmill exercise and subjects were assigned to either a low-aerobic-power (LAP) group
(n = 10) or a high-aerobic-power (HAP) group (n = 11). Mean (SE) ˙VO 2max of the groups were 46.6 (1.1) and 64.4 (1.4) ml · kg−1 · min−1, respectively. A calf ergometry work capacity test was used to assign the same relative exercise intensity to each subject
for the MRS protocol. At least 48 h later, subjects performed the rest (4 min), exercise (2 min) and recovery (10 min) protocol
in a 1.5 T MRS scanner. The relative concentration of phosphocreatine (PCr) was measured throughout the protocol and intracellular
pH (pHi) was determined from the chemical shift between inorganic phospate (Pi) and PCr. End-exercise PCr levels were 27 (3.4) and 25 (3.5)% of resting levels for LAP and HAP respectively. Mean resting
pHi was 7.07 for both groups, and following exercise it fell to 6.45 (0.04) for HAP and 6.38 (0.04) for LAP. Analysis of data
using non-linear regression models showed no differences in the rate of either PCr or pHi recovery. The results suggest that ˙VO2max is a poor predictor of metabolic recovery rate from high-intensity exercise. Differences in recovery rate observed between
individuals with similar ˙VO2max imply that other factors influence recovery.
Accepted: 17 December 1996 相似文献