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At least 433 records · Page 24Linked to original sources
PubMed2002

Expression of an antisense GIGANTEA (GI) gene fragment in transgenic radish causes delayed bolting and flowering.

A late-flowering transgenic radish has been produced by the expression of an antisense GIGANTEA (GI) gene fragment using a floral-dip method. Twenty-five plants were dipped into a suspension of Agrobacterium carrying a 2.5 kb antisense GI gene fragment from Arabidopsis, along with the gusA and bar reporter genes, all under the control of a CaMV 35S promoter. From a total of 1462 seeds harvested from these floral-dipped plants, 16 Basta-resistant T1 plants were found to have GUS activity (transformation efficiency of 1.1%). Southern analysis confirmed the integration of one or two copies of the gusA gene in these herbicide-resistant plants. Expression of the GI gene in T1 plants was much reduced compared to both wildtype plants and plants transformed with pCAMBIA3301 (positive control). In the progenies of eleven T1 plants analysed (T2 generation), all lines showed a significant delay in both bolting and flowering times compared to wildtype and positive control plants, and that, the level of GI transcript was inversely proportional to the time of bolting and flowering. At a maximum, bolting and flowering times were delayed by 17 and 18 days respectively, compared to wildtype plants (in positive control plants, the delay was 23 and 26 days, respectively). Ten of the 11 lines exhibited a significant reduction in plant height compared to wildtype and positive control plants. This study provides evidence that down-regulation of the GI gene by co-suppression could delay bolting in a cold-sensitive long-day (LD) plant. Production of late-flowering germplasms of radish may allow this important crop to be cultivated over an extended period and also provide further food to the famine countries of S/E Asia.

Agrobacterium tumefaciens↗
PubMed2002

Genetic mechanisms of floral trait correlations in a natural population.

Genetic correlations among traits are important in evolution, as they can constrain evolutionary change or reflect past selection for combinations of traits. Constraints and integration depend on whether the correlations are caused by pleiotropy or linkage disequilibrium, but these genetic mechanisms underlying correlations remain largely unknown in natural populations. Quantitative trait locus (QTL) mapping studies do not adequately address the mechanisms of within-population genetic correlations because they rely on crosses between distinct species, inbred lines or selected lines (see ref. 5), and they cannot distinguish moderate linkage disequilibrium from pleiotropy because they commonly rely on only one or two episodes of recombination. Here I report that after nine generations of enforced random mating (nine episodes of recombination), correlations between six floral traits in wild radish plants are unchanged, showing that pleiotropy generates the correlations. There is no evidence for linkage disequilibrium despite previous correlational selection acting on one functionally integrated pair of traits. This study provides direct evidence of the genetic mechanisms underlying correlations between quantitative traits in a natural population and suggests that there may be constraints on the independent evolution of pairs of highly correlated traits.

Biological Evolution↗
PubMed2003

Masticatory laterality--evaluation and influence of food texture.

The purpose of this study is the objective and quantitative evaluation of masticatory laterality and its daily variability. Various foods with different textures were used to investigate whether food texture influenced masticatory laterality. Ten healthy subjects and seven foods were used. Recordings of chewing movements were repeated three times at intervals of 1 week. Masticatory laterality was assessed with an Asymmetry Index [AI: (number of right side strokes - number of left side strokes)/number of total strokes]. Medians and ranges of the three recordings were calculated. The observed AI ranges in the three trials were limited with the exception of two subjects. Among the other subjects, averages of the absolute values of the medians were from 32.5 to 73.4%. Statistically significant differences between the hardest food and softer foods were observed in absolute value of AI medians. Masticatory laterality could be evaluated by an AI. Eight of 10 subjects showed limited ranges of AI in three recordings. It should be noted that a few people actually chew on either side but might chew on one side only on a particular day. Hard food evoked more masticatory laterality, and seemed more appropriate for laterality examinations.

Adult↗
PubMed2003

Genetic characterization of a pentatricopeptide repeat protein gene, orf687, that restores fertility in the cytoplasmic male-sterile Kosena radish.

Cytoplasmic male sterility (CMS) in plants is a maternally inherited inability to produce functional pollen, and is often associated with mitochondrial DNA abnormalities. Specific nuclear loci that suppress CMS, termed as restorers of fertility (Rf), have been identified. Previously, we identified an Rf for the CMS Kosena radish and used genetic analysis to identify the locus and create a contig covering the critical interval. To identify the Rf gene, we introduced each of the lambda and cosmid clones into the CMS Brassica napus and scored for fertility restoration. Fertility restoration was observed when one of the lambda clones was introduced into the CMS B. napus. Furthermore, introduction of a 4.7-kb BamHI/HpaI fragment of the lambda clone is enough to restore male fertility. A cDNA strand isolated from a positive fragment contained a predicted protein (ORF687) of 687 amino acids comprising 16 repeats of the 35-amino acid pentatricopeptide repeat (PPR) motif. Kosena CMS radish plants were found to express an allele of this gene possessing four substituted amino acids in the second and third repeats of the PPR suggesting that the domains formed by these repeats in ORF687 are essential for fertility restoration. Protein levels of the Kosena CMS-associated mitochondrial protein ORF125 were considerably reduced in plants in which fertility was restored, although mRNA expression was normal. Regarding the possible role for PPR-containing proteins in the regulation of the mitochondrial gene, we propose that ORF687 functions either directly or indirectly to lower the levels of ORF125, resulting in the restoration of fertility in CMS plants.

Alleles↗
PubMed2003

The radish Rfo restorer gene of Ogura cytoplasmic male sterility encodes a protein with multiple pentatricopeptide repeats.

A single radish nuclear gene, Rfo, restores Ogura (ogu) cytoplasmic male sterility (CMS) in Brassica napus. A map-based cloning approach relying on synteny between radish and Arabidopsis was used to clone Rfo. A radish gene encoding a 687-amino-acid protein with a predicted mitochondrial targeting pre-sequence was found to confer male fertility upon transformation into ogu CMS B. napus. This gene, like the recently described Petunia Rf gene, codes for a pentatricopeptide repeat (PPR)-containing protein with multiple, in this case 16, PPR domains. Two similar genes that do not appear to function as Rfo flank this gene. Comparison of the Rfo region with the syntenic Arabidopsis region indicates that a PPR gene is not present at the Rfo-equivalent site in Arabidopsis, although a smaller and related PPR gene is found about 40 kb from this site. The implications of these findings for the evolution of restorer genes and other PPR encoding genes are discussed.

Amino Acid Sequence↗
PubMed2003

Changes in some enzymes of microbodies and plastid development in excised radish cotyledons: effect of narciclasine.

Narciclasine (NCS), isolated from mucilage of Narcissus bulb, showed inhibitory effects on growth and plastid development of excised radish cotyledons. NCS (0.1 mumol/L) started to show inhibitory effects on isocitrate lyase and hydroxypyruvate reductase activities after 24 h incubation in light. When NCS concentration was increased to 10 mumol/L, the activities of both enzymes are completely inhibited. From ultrastructural studies, NCS markedly prevented the degradation of protein bodies and lipid bodies, as well as chloroplast formation of excised radish cotyledons. There was only little degradation of protein and lipid bodies, and almost no chloroplast formation in the excised radish cotyledon treated with 1 mumol/L NCS. Therefore, our results provide clear evidence that NCS inhibited the transition of glyoxysomes and peroxisomes, and chloroplast development.

Alcohol Oxidoreductases↗
PubMed2003

Induction of myrosinase gene expression and myrosinase activity in radish hypocotyls by phototropic stimulation.

The role of myrosinase (beta-thioglucoside glucohydrolase, EC 3.2.3.1) in the phototropic response in radish hypocotyls was investigated. Unilateral illumination with blue light abruptly up-regulated the activity of myrosinase, which releases bioactive 4-methylthio-3-butenyl isothiocyanate (MTBI) from inactive 4-methylthio-3-butenyl glucosinolate (MTBG), in the illuminated halves of radish hypocotyls 10 min after onset of phototropic stimulation, peaking after 30 min and decreasing thereafter. The myrosinase activity in the shaded halves also increased, but was significantly lower than that in the illuminated halves. Furthermore, whether blue light illumination induces myrosinase gene expression was studied. Northern blotting analysis indicated that myrosinase mRNA levels were increased markedly in unilaterally illuminated hypocotyls, reaching maximum signal intensity within 10 min after onset of blue illumination, declining nearly to the control level thereafter. These results suggested that phototropic stimulation promotes myrosinase gene expression and myrosinase activity in the illuminated side, resulting in the conversion of inactive MTBG to active MTBI and simultaneously producing more active raphanusanins, causing a phototropic response.

Butyrates↗
PubMed2003

Survey of nitrate and nitrite contents of vegetables grown in Korea.

A scientific basis for the evaluation of the risk to public health arising from excessive dietary intake of nitrate in Korea is provided. The nitrate () and nitrite () contents of various vegetables (Chinese cabbage, radish, lettuce, spinach, soybean sprouts, onion, pumpkin, green onion, cucumber, potato, carrot, garlic, green pepper, cabbage and Allium tuberosum Roth known as Crown daisy) are reported. Six hundred samples of 15 vegetables cultivated during different seasons were analysed for nitrate and nitrite by ion chromatography and ultraviolet spectrophotometry, respectively. No significant variance in nitrate levels was found for most vegetables cultivated during the summer and winter harvests. The mean nitrates level was higher in A. tuberosum Roth (5150 mg kg(-1)) and spinach (4259 mg kg(-1)), intermediate in radish (1878 mg kg(-1)) and Chinese cabbage (1740 mg kg(-1)), and lower in onion (23 mg kg(-1)), soybean sprouts (56 mg kg(-1)) and green pepper (76 mg kg(-1)) compared with those in other vegetables. The average nitrite contents in various vegetables were about 0.6 mg kg(-1), and the values were not significantly different among most vegetables. It was observed that nitrate contents in vegetables varied depending on the type of vegetables and were similar to those in vegetables grown in other countries. From the results of our studies and other information from foreign sources, it can be concluded that it is not necessary to establish limits of nitrates contents of vegetables cultivated in Korea due to the co-presence of beneficial elements such as ascorbic acid and alpha-tocopherol which are known to inhibit the formation of nitrosamine.

Allium↗
PubMed2002

Toxicity and biodegradation of diamines.

Phytotoxicity and cytotoxicity of 2,4-diaminotoluene (2,4-D), 4,4'-methylenedianiline (4,4-D), and 1,6-hexanediamine (1,6-D) were investigated by observing the germination of young radish seeds and the viability of HeLa cells, respectively. 2,4-D showed the highest, 4,4-D intermediate, and 1,6-D lowest cytotoxicity. However, the phytotoxicity decreased in the order of 4,4-D > 2,4-D > 1,6-D. Contrary to the results previously reported, in the modified Sturm test the activated sludge degraded 2,4-D and 4,4-D as well as 1,6-D without any pre-acclimation. Ochrobacterium antropi was isolated for degradation of 2,4-D and 4,4-D and Pseudomonas citronellolis for 1,6-D degradation. Thielevia sp. was isolated as 2,4-D degrading fungus and Aspergillus sp. as 4,4-D and 1,6-D degrading fungus. The fungi degraded the diamines faster than the bacteria.

Aniline Compounds↗
PubMed1950

Ageing and the influx of water into radish root-hair cells.

A micropotometric device previously described by the writer was used to determine quantitatively the velocity of water influx in cubic microns per square micron of hair surface per minute of comparatively older and younger root hairs of radish seedlings in a humid atmosphere at 29 degrees +/- 1 degrees C. when the micropotometers were filled with Hoagland solution at pH 6.8. In each experiment, measurements were made on two hairs of different length and different age on a given root and the hairs were inserted into the micropotometers a sufficient distance so that the area of immersion, 13,200micro(2), was the same in each instance. The range of velocities of water influx through the immersed surface was 4.46 to 1.16micro(3)/micro(2)/min. for the younger and shorter hairs which varied in length from 280 to 460 microns. The range of velocities of water influx through the immersed surface of the older hairs which varied from 661 to 2300 microns in length was 1.94 to 0.47micro(3)/micro(2)/min. The data indicate that water entry slows down in older hairs independent of root length. Estimations were made of the times to replace hair volumes based upon the mean velocities of water entry of the immersed areas. It was found that the time for the hairs to absorb an amount of water equivalent to their own volumes under the conditions specified was a matter of minutes or less; the range was 0.90 to 8.51 minutes.

Hair↗
PubMed2003

A semi-automatic method for developing an anthropomorphic numerical model of dielectric anatomy by MRI.

Complex permittivity values have a dominant role in the overall consideration of interaction between radiofrequency electromagnetic fields and living matter, and in related applications such as electromagnetic dosimetry. There are still some concerns about the accuracy of published data and about their variability due to the heterogeneous nature of biological tissues. The aim of this study is to provide an alternative semi-automatic method by which numerical dielectric human models for dosimetric studies can be obtained. Magnetic resonance imaging (MRI) tomography was used to acquire images. A new technique was employed to correct nonuniformities in the images and frequency-dependent transfer functions to correlate image intensity with complex permittivity were used. The proposed method provides frequency-dependent models in which permittivity and conductivity vary with continuity--even in the same tissue--reflecting the intrinsic realistic spatial dispersion of such parameters. The human model is tested with an FDTD (finite difference time domain) algorithm at different frequencies; the results of layer-averaged and whole-body-averaged SAR (specific absorption rate) are compared with published work, and reasonable agreement has been found. Due to the short time needed to obtain a whole body model, this semi-automatic method may be suitable for efficient study of various conditions that can determine large differences in the SAR distribution, such as body shape, posture, fat-to-muscle ratio, height and weight.

Algorithms↗
PubMed2002

Aquaporin isoforms responsive to salt and water stresses and phytohormones in radish seedlings.

Aquaporins in the plasma and vacuolar membranes play a key role in the intercellular and intracellular water transport in plants. First, we quantitated the absolute amounts for mRNAs of eight aquaporin isoforms in hypocotyls of radish seedlings. Then, we investigated the effects of salt and water stresses (150 mM NaCl, 300 mM mannitol and 20% polyethylene glycol) and phytohormones (gibberellic acid, abscisic acid and brassinolide) on the mRNA and protein levels of aquaporins in the plasma membrane (RsPIP1-1, 1-2, 1-3, 2-1, 2-2 and 2-3) and vacuolar membrane (RsTIP1-1 and 2-1). The mRNA and protein levels of RsTIP1-1, RsTIP2-1, RsPIP1-1, RsPIP1-2 and RsPIP1-3 were comparatively constant. In contrast, mannitol treatment altered the mRNA levels of RsPIP2-1, RsPIP2-2 and RsPIP2-3 in roots. Immunoblot analysis showed that the RsPIP2-1 protein level was increased by NaCl treatment and decreased by treatment with mannitol and polyethylene glycol. Gibberellic acid and abscisic acid suppressed the levels of mRNAs of RsPIP2-1, RsPIP2-2 and RsPIP2-3 and the protein level of RsPIP2-1 in roots. On the other hand, the protein levels of RsPIP1-group members and RsTIPs were scarcely changed by these phytohormones. In the case of hypocotyls and cotyledons, the mRNA and protein levels of eight isoforms were not markedly affected by any treatment. These results indicate that aquaporins in the root, especially the RsPIP2 group, may be a stress responsive type of aquaporin at least in the protein level.

Abscisic Acid↗
PubMed2003

Differences in aquaporin levels among cell types of radish and measurement of osmotic water permeability of individual protoplasts.

We investigated tissue- and cell-specific accumulation of radish aquaporin isoforms by immunocytochemical analysis. In taproots, the plasma membrane aquaporins (RsPIP1 and RsPIP2) were accumulated at high levels in the cambium, while the tonoplast aquaporin (RsTIP) was distributed in all tissues. The three isoforms were highly accumulated in the central cylinder of seedling roots and hypocotyls, and rich in the vascular tissue of the petiole of mature plants. The results suggest that RsPIP1 and RsPIP2 are abundant in the cells surrounding the sieve tube of the radish plant. The swelling rate of protoplasts in a hypotonic solution was determined individually by a newly established method to compare the osmotic water permeability of different cell types. All cells of the cortex and endodermis in seedlings showed a high water permeability of more than 300 microm s(-1). There was no marked difference in the values between the root endodermis and cortex protoplasts, although the RsPIP level was lower in the cortex than in the endodermis. This inconsistency suggests two possibilities: (1) a low level of aquaporin is enough for high water permeability and (2) the water channel activity of aquaporin in the tissues is regulated individually. The uneven distribution of aquaporins in tissues is discussed along with their physiological roles.

Algorithms↗
PubMed2005

Effects of elevated CO2 on the capacity for photosynthesis of a single leaf and a whole plant, and on growth in a radish.

The atmospheric concentration of CO2 will probably rise to about 700 micromol mol(-1) by the end of this century. The effects of elevated growth CO2 on photosynthesis are still not fully understood. Effects of elevated growth CO2 on the capacity for photosynthesis of a single leaf and a whole plant were investigated with the radish cultivar White Cherish. The plants were grown under ambient ( approximately 400 micromol mol(-1)) or elevated CO2 ( approximately 750 micromol mol(-1)). The rates of net photosynthesis per leaf area with a whole plant and a single leaf of plants of various ages (15-26 d after planting) were measured under ambient and elevated CO2. The rates of photosynthesis were increased by 20-28% by elevated CO2. There was no effect of elevated growth CO2 on the rate of photosynthesis, clearly indicating no downward acclimation of photosynthesis to elevated CO2. Elevated CO2 increased dry weight accumulation by >27%. The effect of elevated CO2 on other growth characteristics will also be shown.

Carbon Dioxide↗