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921.
Novel iron-storage particles may play a role in aluminum tolerance of Cyanidium caldarium 总被引:1,自引:0,他引:1
Cyanidium caldarium (Tilden) Geitler, a unicellular red alga, has extraordinarily high aluminum (Al) tolerance. Algal cells cultured in the presence or absence of Al were subjected to transmission electron microscopy and energy dispersive X-ray analysis. Substantial changes to the thylakoid lumens were observed for the algal cells cultured in medium containing 200 mM Al, while other organelles were largely unaffected. Several spherical electron-dense bodies were found in the cytoplasm near the nucleus of both of the control and Al-treated cells. Although high levels of Fe and P were found in the bodies of control cells, immunocytochemical and morphological analysis data did not match the criteria established for Fe-accumulating substances like ferritin and phytate. In addition to these elements, Al was found in the bodies of the Al-treated cells. These results suggest that the electron-dense bodies function as an Fe-storage site under normal culture conditions, and that sequestration of Al in these bodies contributes to the high Al tolerance exhibited by C. caldarium. 相似文献
922.
Mapping quantitative trait loci controlling seed longevity in rice ( Oryza sativa L.) 总被引:1,自引:0,他引:1
Miura K Lin Y Yano M Nagamine T 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(6-7):981-986
Quantitative trait loci (QTLs) controlling seed longevity in rice were identified using 98 backcross inbred lines (BILs) derived from a cross between a japonica variety Nipponbare and an indica variety Kasalath. Seeds of each BIL were kept for 12 months at 30 degrees C in dry conditions to promote loss of viability. To measure seed longevity, we performed an additional aging-processing treatment for 2 months at 30 degrees C maintaining seeds at 15% moisture content. We measured the germination percent of these treated seeds at 25 degrees C for 7 days as the degree of seed longevity. The germination of BILs ranged from 0 to 100% with continuous variation. Three putative QTLs for seed longevity, qLG-2, qLG-4 and qLG-9, were detected on chromosome 2, 4 and 9, respectively. Kasalath alleles increased the seed longevity at these QTLs. The QTL with the largest effect, qLG-9, explained 59.5% of total phenotypic variation in BILs. The other two QTLs, qLG-2 and qLG-4, explained 13.4 and 11.6% of the total phenotypic variation, respectively. We also verified the effect of the Kasalath allele of qLG-9 using chromosome segment substitution lines. Furthermore, QTLs for seed dormancy were identified on chromosomes 1, 3, 5, 7 and 11. Based on the comparison of the chromosomal location of QTLs for seed longevity and seed dormancy, these traits seem to be controlled by different genetic factors. 相似文献
923.
Richerson and Boyd proposed a model of sexual selection in which both the male trait and the female preference are culturally transmitted. We generalize their model by introducing sex-dependent oblique transmission rates and a fairly comprehensive female preference rule. The model differs markedly from the standard genetic models in that the male trait and the female preference are uncorrelated. Hence, there can be no "sexy son" effect to offset the assumed fertility cost to choosy females. Nevertheless, the cultural processes can support a stable polymorphic equilibrium at which the choosy females are present. Also of interest are the cyclical dynamics observed in the neighborhood of the internal equilibrium. 相似文献
924.
Yoshiharu Nishida Kenichi Hirano Kosuke Tsukamoto Makoto Nagano Chiaki Ikegami Kirsten Roomp Mitsuaki Ishihara Naoki Sakane Zhongyan Zhang Ken-ichi Tsujii Ki Akifumi Matsuyama Tohru Ohama Fumihiko Matsuura Masato Ishigami Naohiko Sakai Hisatoyo Hiraoka Hiroaki Hattori Cheryl Wellington Yoshihide Yoshida Susumu Misugi Michael R Hayden Toru Egashira Shizuya Yamashita Yuji Matsuzawa 《Biochemical and biophysical research communications》2002,290(2):713-721
ATP-binding cassette transporter-1 (ABCA1) gene is mutated in patients with familial high-density lipoprotein deficiency (FHD). In order to know the molecular basis for FHD, we characterized three different ABCA1 mutations associated with FHD (G1158A/A255T, C5946T/R1851X, and A5226G/N1611D) with respect to their expression in the passaged fibroblasts from the patients and in the cells transfected with the mutated cDNAs. Fibroblasts from the all patients showed markedly decreased cholesterol efflux to apolipoprotein (apo)-Al. In the fibroblasts homozygous for G1158A/A255T, the immunoreactive mass of ABCA1 could not be detected, even when stimulated by 9-cis-retinoic acid and 22-R-hydroxycholesterol. In the fibroblasts homozygous for C5946T/R1851X, ABCA1 mRNA was comparable. Because the mutant ABCA1 protein (R1851X) was predicted to lack the epitope for the antibody used, we transfected FLAG-tagged truncated mutant (R1851X/ABCA1-FLAG) cDNA into Cos-7 cells, showing that the mutant protein expression was markedly reduced. The expression of N1611D ABCA1 protein was comparable in both fibroblasts and overexpressing cells, although cholesterol efflux from the cells was markedly reduced. These data indicated that, in the three patients investigated, the abnormalities and dysfunction of ABCA1 occurred at the different levels, providing important information about the expression, regulation, and function of ABCA1. 相似文献
925.
Cinco RM McFarlane Holman KL Robblee JH Yano J Pizarro SA Bellacchio E Sauer K Yachandra VK 《Biochemistry》2002,41(43):12928-12933
The proximity of Ca to the Mn cluster of the photosynthetic water-oxidation complex is demonstrated by X-ray absorption spectroscopy. We have collected EXAFS data at the Ca K-edge using active PS II membrane samples that contain approximately 2 Ca per 4 Mn. These samples are much less perturbed than previously investigated Sr-substituted samples, which were prepared after Ca depletion. The new Ca EXAFS clearly shows backscattering from Mn at 3.4 A, a distance that agrees with that surmised from previously recorded Mn EXAFS. This result is also consistent with earlier related experiments at the Sr K-edge, using samples that contained functional Sr, that show Mn is approximately 3.5 A distant from Sr. The totality of the evidence clearly advances the notion that the catalytic center of oxygen evolution is a Mn-Ca heteronuclear cluster. 相似文献
926.
Kimitaka Nakazawa Hideo Yano Hiroyuki Satoh Iwao Fujisaki 《European journal of applied physiology and occupational physiology》1998,77(5):395-400
Stretch reflexes were evoked in elbow flexor muscles undergoing three different muscle contractions, i.e. isotonic shortening
(SHO) and lengthening (LEN), and isometric (ISO) contractions. The intermuscle relationships for the magnitude of the stretch
reflex component in the eletromyographic (EMG) activities of two main elbow flexor muscles, i.e. the biceps brachii (BB) and
the brachioradialis (BRD), were compared among the three types of contractions. The subjects were requested to move their
forearms sinusoidally (0.1 Hz) against a constant pre-load between elbow joint angles of 10° (0° = full extension) and 80°
during SHO and LEN, and to keep an angle of 45° during the ISO. The perturbations were applied at the elbow angle of 45° in
pseudo-random order. The EMG signals were rectified and averaged over a period of 100 ms before and 400 ms after the onset
of the perturbation 40–50 times. From the ensemble averaged EMG waveform, the background activity (BGA), short (20–50 ms)
and long latency (M2, 50–80, M3, 80–100 ms) reflex and voluntary activity (100–150 ms) components were measured. The results
showed that both BGA and reflex EMG activity of the two elbow flexor muscles were markedly decreased during the lengthening
contraction compared to the SHO and ISO contractions. Furthermore, the changes of reflex EMG components in the BRD muscle
were more pronounced than those in the BB muscle, i.e. the ratios of M2 and M3 magnitudes between BRD and BB (BRD:BB) were
significantly reduced during the LEN contractions. These results would suggest that the gain of long latency stretch reflex
EMG activities in synergistic muscles might be modulated independently according to the model of muscle contraction.
Accepted: 1 September 1997 相似文献
927.
Toshio Itoh T. Tanaka Ryozo Nagai Kenjiro Kikuchi Satoshi Ogawa Shintaro Okada Shiro Yamagata Katsusuke Yano Yoshio Yazaki Yusuke Nakamura 《Human genetics》1998,103(3):290-294
To elucidate the role of the KVLQT1 gene in the pathogenesis of long QT syndrome (LQTS), we have established a screening system for detecting KVLQT1 mutations by the polymerase chain reaction-single strand conformation polymorphism technique (PCR-SSCP). We first determined
exon/intron boundaries and flanking intronic sequences, and found that the KVLQT1 gene consists of 17 coding exons. Subsequently, we synthesized oligonucleotide primers to cover the coding region and the
flanking intronic sequences, and searched for mutations in 31 Japanese LQTS families. When genomic DNA from each proband was
examined by PCR-SSCP followed by direct DNA sequencing, mutations were detected in five families; two independent families
carried the same mutation and three of the four were novel. Each mutation was present in affected relatives of the respective
proband. This work will enable us to search more thoroughly for LQTS mutations associated with KVLQT1, and eventually will help us in finding genotype/phenotype relationships.
Received: 20 March 1998 / Accepted: 30 April 1998 相似文献
928.
M. Wissuwa M. Yano N. Ae 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(5-6):777-783
Phosphorus (P) deficiency of soils is a major yield-limiting factor in rice production. Increasing the P-deficiency tolerance
of rice cultivars may represent a more cost-effective solution than relying on fertilizer application. The objective of this
study was to identify putative QTLs for P-deficiency tolerance in rice, using 98 backcross inbred lines derived from a japonica×indica cross and genotyped at 245 RFLP marker loci. Lines were grown on P-deficient soil and P uptake, internal P-use efficiency,
dry weight, and tiller number were determined. Three QTLs were identified for dry weight and four QTLs for P uptake, together
explaining 45.4% and 54.5% of the variation for the respective traits. Peaks for both traits were in good agreement which
was to be expected considering the tight correlation of r=0.96 between dry weight and P uptake. For both traits the QTL linked to marker C443 on chromosome 12 had a major effect.
Two of the three QTLs detected for internal P-use efficiency, including the major one on chromosome 12, coincided with QTLs
for P uptake; however, whereas indica alleles increased P uptake they reduced P-use efficiency. We concluded that this was not due to the tight linkage of two
genes in repulsion but rather due to an indirect effect of P uptake on P-use efficiency. Most lines with high use efficiency
were characterized by very low P uptake and dry weight and apparently experienced extreme P-deficiency stress. Their higher
P-use efficiency was thus the result of highly sub-optimal tissue-P concentrations and did not represent a positive adaptation
to low P availability. The number of tillers produced under P deficiency is viewed as an indirect indicator of P-deficiency
tolerance in rice. In addition to the major QTL on chromosome 12 already identified for all other traits, two QTLs on chromosome
4 and 12 were identified for tiller number. Their position, however, coincided with QTLs for tiller number reported elsewhere
under P-sufficient conditions and therefore appear to be not related to P-deficiency tolerance. In this study P-deficiency
tolerance was mainly caused by differences in P uptake and not in P-use efficiency. Using a trait indirectly related to P-deficiency
tolerance such as tiller number, we detected a major QTL but none of the minor QTLs detected for P uptake or dry weight.
Received: 9 February 1998 / Accepted: 29 April 1998 相似文献
929.
Mapping quantitative trait loci controlling seed dormancy and heading date in rice, Oryza sativa L., using backcross inbred lines 总被引:21,自引:0,他引:21
S. Y. Lin T. Sasaki M. Yano 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(8):997-1003
To detect quantitative trait loci (QTLs) controlling seed dormancy, 98 BC1F5 lines (backcross inbred lines) derived from a backcross of Nipponbare (japonica)/Kasalath (indica)//Nipponbare were analyzed genetically. We used 245 RFLP markers to construct a framework linkage map. Five putative QTLs
affecting seed dormancy were detected on chromosomes 3, 5, 7 (two regions) and 8, respectively. Phenotypic variations explained
by each QTL ranged from 6.7% to 22.5% and the five putative QTLs explained about 48% of the total phenotypic variation in
the BC1F5 lines. Except for those of the QTLs on chromosome 8, the Nipponbare alleles increased the germination rate. Five putative
QTLs controlling heading date were detected on chromosomes 2, 3, 4, 6 and 7, respectively. The phenotypic variation explained
by each QTL for heading date ranged from 5.7% to 23.4% and the five putative QTLs explained about 52% of the total phenotypic
variation. The Nipponbare alleles increased the number of days to heading, except for those of two QTLs on chromosomes 2 and
3. The map location of a putative QTL for heading date coincided with that of a major QTL for seed dormancy on chromosome
3, although two major heading-date QTLs did not coincide with any seed dormancy QTLs detected in this study.
Received: 10 October 1997 / Accepted: 12 January 1998 相似文献
930.
Fine mapping of quantitative trait loci Hd-1, Hd-2 and Hd-3, controlling heading date of rice, as single Mendelian factors 总被引:32,自引:0,他引:32
T. Yamamoto Y. Kuboki S. Y. Lin T. Sasaki M. Yano 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(1-2):37-44
Fine mapping was carried out on three putative QTLs (tentatively designated as Hd-1 to Hd-3) of five such QTLs controlling heading date in rice that had been earlier identified using an F2 population derived from a cross between a japonica variety, ‘Nipponbare’, and an indica variety, ‘Kasalath’, using progeny backcrossed with ‘Nipponbare’ as the recurrent parent. One BC3F2 and two BC3F1 plants, in which the target QTL regions were heterozygous and most other chromosomal regions were homozygous for the ‘Nipponbare’
allele, were selected as the experimental material. Self-pollinated progeny (BC3F2 and BC3F3) of the BC3F1 or BC3F2 showed continuous variation in days to heading. By means of progeny testing based on BC3F3 or BC3F4 lines, we determined the genotypes of each BC3F2 or BC3F3 individual at target QTLs. Their segregation patterns fitted Mendelian inheritance ratios. When the results obtained by RFLP
analysis and progeny tests were combined, Hd-1, Hd-2 and Hd-3 were mapped precisely on chromosomes 6, 7 and 6, respectively, of a rice RFLP linkage map. The results demonstrated that
QTLs can be treated as Mendelian factors. Moreover, these precise locations were in good agreement with the regions estimated
by QTL analysis of the initial F2 population, demonstrating the high reliability of QTL mapping using a high-density linkage map.
Received: 5 November 1997 / Accepted: 10 February 1998 相似文献