Showing papers by "Kagawa University published in 2000"

Role of Organic Acids in Detoxification of Aluminum in Higher Plants

Abstract: Phytotoxicity of aluminum ion (Al3+) is a serious problem limiting crop production on acid soils. Organic acids with Al-chelating ability play an important role in the detoxification of Al both externally and internally. Al is detoxified externally by the secretion of organic acids such as citric, oxalic, and/or malic acids from the roots. The secretion of organic acids is highly specific to Al and the site of secretion is localized to the root apex. The kind of organic acids secreted as well as secretion pattern differ among plant species. There are two patterns of Al-induced secretion of organic acids: In pattern I, there is no discernible delay between the addition of Al and the onset of the release of organic acids. Activation of the anion channel seems to be involved in this pattern; In pattern II, there is a marked lag phase between the addition of Al and the onset of organic acid release. The action of genes related to the metabolism and secretion of organic acids seems to be involved in this pattern. Internal detoxification of Al in Al-accumulating plants is achieved by the formation of Al-organic acid complex. For instance, the complex of Al-citrate (1:1) in hydrangea and Al-oxalate (1:3) in buckwheat has been identified.

Alteration in Left Ventricular Diastolic Filling and Accumulation of Myocardial Collagen at Insulin-Resistant Prediabetic Stage of a Type II Diabetic Rat Model

Abstract: Background—Considerable controversy exists regarding impairment of cardiac function in diabetes mellitus (DM). We investigated the serial changes in left ventricular (LV) histopathology and LV filling dynamics in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, which have been established as an animal model of type II DM. Methods and Results—In 54 OLETF and 54 non-DM rats, body weight, blood pressure, heart rate, and transmitral pulsed Doppler examinations were performed from 5 to 47 weeks of age. An oral glucose tolerance test was performed at 10, 20, and 30 weeks of age. The hearts were excised for histopathology, including immunohistochemistry and histomorphometry of collagen, and measurement of hydroxyproline at baseline and each stage of developing DM. In the prediabetic stage (15 weeks of age), in which fast blood glucose remained normal, OLETF rats manifested mild obesity, postprandial hyperglycemia, and hyperinsulinemia, and early diastolic transmitral inflow exhibited prolonged deceleration time (...

Pattern of Aluminum-Induced Secretion of Organic Acids Differs between Rye and Wheat

Abstract: Al-Induced secretion of organic acids from the roots has been considered as a mechanism of Al tolerance, but the processes leading to the secretion of organic acids are still unknown. In this study, the secretion pattern and alteration in the metabolism of organic acids under Al stress were examined in rye (Secale cereale L. cv King) and wheat (Triticum aestivum L. cv Atlas 66). Al induced rapid secretion of malate in the wheat, but a lag (6 and 10 h for malic and citric acids, respectively) between the exposure to Al and the secretion of organic acids was observed in the rye. The activities of isocitrate dehydrogenase, phosphoenolpyruvate carboxylase, and malate dehydrogenase were not affected by Al in either plant. The activity of citrate synthase was increased by the exposure to Al in the rye, but not in the wheat. The secretion of malate was not suppressed at low temperature in the wheat, but that of citrate was stopped in the rye. The Al-induced secretion of citrate from roots of the rye was inhibited by the inhibitors of a citrate carrier, which transports citrate from the mitochondria to the cytoplasm. All of these results suggest that alteration in the metabolism of organic acids is involved in the Al-induced secretion of organic acids in rye, but only activation of an anion channel seems to be responsible for the rapid secretion of malate in the wheat.

Form of aluminium for uptake and translocation in buckwheat (Fagopyrum esculentum Moench)

Abstract: The forms of Al for uptake by the roots and translocation from the root to the shoot were investigated in a buckwheat (Fagopyrum esculentum Moench, cv. Jianxi) that accumulates Al in its leaves. The Al concentration in the xylem sap was 15-fold higher in the plants exposed to AlCl3 than in those exposed to an Al-oxalate (1:3) complex, suggesting that the roots take up Al in the ionic form. The Al concentration in the xylem sap was 4-fold higher than that in the external solution after a 1-h exposure to AICl3 solution and 10-fold higher after a 2-h exposure. The Al concentration in the xylem sap increased with increasing Al concentration in the external solution. The Al uptake was not affected by a respiratory inhibitor, hydroxylamine, but significantly inhibited by the addition of La. These results suggest that Al uptake by the root is a passive process, and La3+ competes for the binding sites for Al3+ on the plasma membrane. The form of Al in the xylem sap was identified by 27Al-nuclear magnetic resonance analysis. The chemical shift of 27Al in the xylem sap was around 10.9 ppm, which is consistent with that of the Al-citrate complex. Furthermore, the dominant organic acid in the xylem sap was citric acid, indicating that Al was translocated in the form of Al-citrate complex. Because Al is present as Al-oxalate (1:3) in the root, the present data show that ligand exchange from oxalate to citrate occurs before Al is released to xylem.

Aluminum Tolerance Genes on the Short Arm of Chromosome 3R Are Linked to Organic Acid Release in Triticale

Abstract: Triticale, a hybrid between wheat and rye, shows a high degree of Al tolerance that is inherited from rye, but the mechanisms of high Al tolerance in both rye and triticale are unknown. We found that the short arm of chromosome 3R carries genes necessary for Al tolerance in triticale (x Triticosecale Wittmark cv Currency). Detailed comparative studies with a 3DS.3RL translocation line (ST22) and a non-substitution line (ST2) were conducted. Root elongation was similarly inhibited by Al in ST2 and ST22 during the first 12 h of Al treatment, but more strongly in ST22 than in ST2 at 18 h and thereafter. The root inhibition induced by other metals (Cu, Cd, and La) was similar between ST2 and ST22, suggesting that the action of the genes for Al tolerance on the short arm of triticale chromosome 3R is highly specific to Al. A 2-fold larger amount of malate and citrate was released from the roots of ST2 than from ST22 at 12 and 18 h after Al treatment, respectively. The marked lag phase in the inhibition of root elongation and the release of organic acids implies that the expression of genes on the short arm of triticale chromosome 3R is induced by Al, and that these genes are necessary for the release of organic acids.

Relations between Surface Temperature and Air Temperature on a Local Scale during Winter Nights

Abstract: The relations between surface temperature and air temperature on clear winter nights were investigated with regard to spatial scale and the vegetation effect at a local meteorological scale. The study was based on nighttime images obtained from the Landsat Thematic Mapper and high-density meteorological data obtained from the Automated Meteorological Data Acquisition System (AMeDAS). The correlation coefficients between the air temperatures and the surface temperatures at the AMeDAS stations were relatively high despite the simple comparison. Surface temperature alone explained 80% of the observed variation in air temperature. The spatial scales of the effect of surface temperature on air temperature and the effect of vegetation density on air temperature were related to the mean lapse rate of the atmospheric boundary layer. Air temperature was more sensitive to vegetation density when the mean lapse rate of the atmospheric boundary layer was smaller. Accuracy in the estimation of air temperature from satellite-derived surface temperature data was improved by multiple regression using the spatially averaged surface temperature and normalized difference vegetation index.

Alternaria mycotoxins in weathered wheat from China.

Abstract: This is the first report of the natural occurrence of Alternaria mycotoxins in Chinese wheat. Wheat kernels were significantly invaded by Alternaria species, mostly A. alternata, with an average infection frequency of 87.3%. A total of 22 samples of weathered wheat kernels from the 1998 crop, representing three locations in the suburbs of Beijing, China, were examined for the presence of Alternaria mycotoxins by high-performance liquid chromatography. Alternariol (AOH) was detected in 20 of 22 samples ranging between 116 and 731 microgram/kg (mean = 335 microgram/kg) and alternariol methyl ether (AME) at a mean level of 443 microgram/kg (range = 52-1426 microgram/kg) in 21 samples. The presence of tenuazonic acid (TA), a major Alternaria toxin in terms of quantity, was detected in all samples analyzed at an average concentration of 2419 microgram/kg with a maximum of 6432 microgram/kg. All samples were free from altertoxin I and altenuene. Samples with high levels of AOH and AME also contain a high level of TA. There was significant linear regression of correlations between the levels of AOH over AME (r = 0.850) and total benzopyrone derivatives (AOH + AME) over TA (r = 0.796).

Dielectric-relaxation spectroscopy of kaolinite, montmorillonite, allophane, and imogolite under moist conditions

Abstract: The dielectric behavior of kaolinite, montmorillonite, allophane, and imogolite samples adjusted to a water potential of 33 kPa was examined using a time-domain reflectometry method over a wide frequency range of 103-1010 Hz. A dielectric relaxation peak owing to bound H2O was observed. The observation of this peak required the precise determination of the contributions of dc conductivity. The peak is located at 10 MHz, indicating that the relaxation time of the bound H2O is approximately ten times longer than the relaxation time of bound H2O with organic polymers, such as an aqueous globular-protein solution. The structure of bound H2O differs between phyllosilicates and amorphous phases, based on differences in relaxation strength and the pattern of distribution of the relaxation times. The dielectric process involving rotation of bulk H2O molecules was also observed at 20 GHz. The relaxation strength of bulk H2O increased with an increase in the water content. The interfacial polarization in the diffuse double layer occurred only in montmorillonite and kaolinite, indicating that mechanisms involving the Maxwell-Wagner and surface-polarization effects cannot be extended to include allophane and imogolite. Although these results suggest that additional work is required, a tentative conclusion is that a tangential migration of counter-ions along clay surfaces may be important.

Geology of the Kokchetav UHP‐HP metamorphic belt, Northern Kazakhstan

Abstract: Ultrahigh-pressure metamorphic (UHPM) rocks of the Kokchetav Massif of Kazakhstan contain metamorphic microdiamond and coesite inclusions inside rigid capsules such as garnet and zircon. Precambrian protoliths of the UHPM rocks were metamorphosed at around 530 Ma, at pressures of about 7 GPa, which suggests that crustal protoliths were subducted to depths of over 200 km. Primary UHPM minerals are poorly preserved due to partial obliteration by subsequent Barrovian overprint during exhumation and later collision events in Caledonian times. We report the results of detailed mapping of the Kokchetav Massif and use structural data to propose intrusion and exhumation mechanisms for the UHPM rocks. Detailed mapping revealed that many subvertical structures in the ultrahigh-pressure–high-pressure (UHP–HP) units were formed due to later folding. The primary structure appears to be subhorizontal and the total thickness of the UHP rocks is estimated at around 2 km. The first order structure is sandwich-like; that is, the UHP–HP units are separated from underlying low-P metamorphic rocks of the Daulet Series and from feebly metamorphosed to unmetamorphosed sedimentary strata on the top by subhorizontal faults. Kinematic indicators show top-to-the-south sense of shear along the top, and top-to-the-north displacement along the bottom boundaries. These shear senses, together with the observed metamorphic gradients, suggest that the thin UHPM sheet was extruded toward the north. We consider wedge extrusion to have been the most effective mechanism for the exhumation of the UHPM rocks.

Sequential changes of KL-6 in sera of patients with interstitial pneumonia associated with polymyositis/dermatomyositis.

Abstract: Objective—KL-6 is a mucin-like high molecular weight glycoprotein, which is strongly expressed on type II alveolar pneumocytes and bronchiolar epithelial cells. It has been demonstrated that the KL-6 antigen is a useful marker for estimating the activity of interstitial pneumonia. In this study, it is hypothesised that serum KL-6 is a useful marker to evaluate the activity of interstitial pneumonia associated with polymyositis/ dermatomyositis (PM/DM). Methods—KL-6 was measured in sera in 16 patients diagnosed with PM/DM. Five had non-specific interstitial pneumonia (NSIP), three had diVuse alveolar damage (DAD), and eight had no pulmonary involvement, and 10 were normal nonsmokers as a control group. The correlation was also evaluated between the KL-6 level and each clinical course in patients with pulmonary involvement associated with PM/DM. Immunohistochemical analysis using monoclonal anti-KL-6 antibody was also performed. Results—KL-6 concentrations in sera of patients with interstitial pneumonia associated with PM/DM were significantly high compared with those of PM/DM without interstitial pneumonia, and normal non-smokers. KL-6 concentrations in sera in patients with DAD significantly increased compared with those of other groups. KL-6 values in sera changed according to the progression or improvement of interstitial pneumonia. Immunohistochemical study using pulmonary tissues obtained from patients with DAD demonstrated that the hyaline membrane, proliferating type II pneumocytes, bronchial epithelial cells and some endothelial cells in pulmonary veins were stained by antihuman KL-6 antibody. Conclusion—These data demonstrate that measurement of serum KL-6 was a useful marker to evaluate the activity of acute interstitial pneumonia associated with PM/DM.

LKP1 (LOV kelch protein 1): a factor involved in the regulation of flowering time in arabidopsis.

Abstract: In plants, light is not only an energy source but also a very important signal that modulates development and differentiation. Here, we report a putative photo-regulatory factor sequence in LKP1 (LOV kelch protein 1). LKP1 cDNA encodes a protein of 610 amino acids and with a molecular weight of 65 905 with an LOV domain and kelch repeats. LOV domains are present in a number of sensor proteins involved in the detection of light, oxygen or voltage. The LKP1 LOV is very similar to the LOV domains in NPH1, a plasma membrane-associated blue light receptor kinase that regulates phototropism (Huala, E., Oeller, P.W., Liscum, E., Han, I-S., Larsen, E. & Briggs, W.R. (1997) Science, 278, 2120-2123). LKP1 mRNA accumulates in roots, stems, flowers and siliques. It is most abundant in leaves, and least abundant in seeds. Transgenic plants with a beta-glucuronidase (GUS) reporter gene driven by a 1.5 kb LKP1 promoter display strong GUS activity in leaves. Transgenic plants with a 35S:LKP1 cDNA gene overexpress LKP1 mRNA. These plants have elongated hypocotyls and petioles with elongated cells, and exhibit distinct cotyledon movement during the day. Expression of 35S:LKP1 in transgenic Arabidopsis promotes late flowering in plants grown under long-day, but not under short-day conditions. Vernalization does not affect the late flowering phenotype of the 35S:LKP1 plants. Transgenic plants possessing the 35S:GFP-LKP1 construct also have long hypocotyles and petioles, and a late flowering phenotype, suggesting that the GFP-LKP1 fusion protein is active. The GFP-associated fluorescence in 35S:GFP-LKP1 plants is observed in nuclei and cytosol, indicating that LKP1 is a new nucleo-cytoplasmic factor that influences flowering time in the long day pathway of Arabidopsis.

Immunochemical and structural analysis of pepsin-digested egg white ovomucoid

Abstract: Ovomucoid, an egg protein comprising ∼10% egg white, was digested using the enzyme pepsin, and fragments were isolated by anion-exchange and reverse phase HPLC. Four distinct fragments were identified by analysis with SDS−PAGE, including three large fragments with molecular weights of around 24, 18, and 14 kDa. N- and C-terminal and amino acid sequencing analyses identified the fragments as V134−C186 (domain 3), V21−A133, and A1−A133 (domain 1+2). Further separation and sequencing of the fraction composed of small peptides, to determine their exact makeup and location in the protein, remained to be carried out and identified a peptide G51−Y73. All four fragments showed IgE-binding activity, as measured by ELISA, using human sera from egg-allergic individuals. Little change in the digestibility of ovomucoid by trypsin and chymotrypsin was observed following digestion with pepsin, indicating that pepsin-digested ovomucoid retains its trypsin (protease) inhibitor activities. Reduced carboxymethylated ovomuco...

Distribution and Characterization of AKT Homologs in the Tangerine Pathotype of Alternaria alternata.

Abstract: The tangerine pathotype of Alternaria alternata produces a host-selective toxin (HST), known as ACT-toxin, and causes Alternaria brown spot disease of citrus. The structure of ACT-toxin is closely related to AK- and AF-toxins, which are HSTs produced by the Japanese pear and strawberry pathotypes of A. alternata, respectively. AC-, AK-, and AF-toxins are chemically similar and share a 9,10-epoxy-8-hydroxy-9-methyl-decatrienoic acid moiety. Two genes controlling AK-toxin biosynthesis (AKT1 and AKT2) were recently cloned from the Japanese pear pathotype of A. alternata. Portions of these genes were used as heterologous probes in Southern blots, that detected homologs in 13 isolates of A. alternata tangerine pathotype from Minneola tangelo in Florida. Partial sequencing of the homologs in one of these isolates demonstrated high sequence similarity to AKT1 (89.8%) and to AKT2 (90.7%). AKT homologs were not detected in nine isolates of A. alternata from rough lemon, six isolates of nonpathogenic A. al...

Difference in Intensity of Ant Defense among Three Species of Macaranga Myrmecophytes in a Southeast Asian Dipterocarp Forest1

Abstract: To examine interspecific variation in the intensity of ant defense among three sympatric species of obligate myrmecophytes of Macaranga (Euphorbiaceae), we measured the ratio of ant biomass to plant biomass, ant aggressiveness to artificial damage on host plants, and increase in herbivore damage on host plants when symbiont ants were removed. Increase in herbivore damage from two- and four-week ant exclusion varied significantly among the three species. The decreasing order of vulnerability to herbivory was M. winkleri, M. trachyphylla, and M. beccariana. The ant/plant biomass ratio (= rate of the dry weight of whole ant colonies to the dry weight of whole aboveground plant parts) and ant agressiveness also varied significantly among the three species; the orders of both the ant/plant biomass ratio and ant aggressiveness were the same as in the herbivory increase. These results indicated that the intensity of ant defense differs predictably among sympatric species of obligate myrmecophytes on Mac...

The role of gibberellin biosynthesis in the control of growth and flowering in Matthiola incana

Abstract: Recently, it was found that stem elongation and flowering of stock Matthiola incana (L.) R. Br. are promoted by exogenous gibberellins (GAs), including GA4, and also by acylcyclohexanedione inhibitors of GA biosynthesis, such as prohexadione-calcium (PCa) and trinexapac-ethyl (TNE). Here, because it was unclear how GA biosynthetic inhibitors could promote stem elongation and flowering, their effect on GA biosynthesis has been examined by quantifying endogenous GA levels; also, the sensitivity of stem elongation and flowering to various GAs in combination with the inhibitors was examined. Stem elongation and flowering were most effectively promoted by GA4 when combined with PCa and, next in order, by 2,2-dimethyl-GA4, PCa, GA4+TNE, TNE, GA9+PCa and by GA4. There was little or no promotion by GA1, GA3, GA9, GA13, GA20 and 3-epi-2,2-dimethyl-GA4. Both the promotive effects of the acylcyclohexanediones on stem elongation and flowering, particularly when applied with GA4, and the fact that TNE caused a build-up of endogenous GA4 imply that one effect of TNE at the lower dose involved an inhibition of 2β-hydroxylation of GA4 rather than an inhibition of 20-oxidation and 3β-hydroxylation of GAs which were precursors of GA4. Overall, these results indicate that: (1) GAs with 3β-OH and without 13-OH groups (e.g. GA4) are the most important for stem elongation and flowering in M. incana; (2) growth promotion rather than inhibition can result if an acylcyclohexanedione acts predominantly to slow 2β-hydroxylation and so slows inactivation of active gibbberellins, including GA4. It follows that a low dose of an acylcyclohexanedione can be a ‘growth enhancer’ for any applied GA that is liable to inactivation by 2β-hydroxylation.

Prevention of doxorubicin (adriamycin)-induced cardiomyopathy by simultaneous administration of angiotensin-converting enzyme inhibitor assessed by acoustic densitometry.

Abstract: The purpose of our study has to determine the myocardial protective effects of the angiotensin-converting enzyme (ACE) inhibitor temocapril (TEM, 7 mg/kg/day) simultaneously administered with doxorubicin (Adriamycin). Twenty male Sprague-Dawley rats were intraperitoneally administered a cumulative dose of 15 mg/kg of doxorubicin (each dose of 1.0 mg/kg x 15) for 3 weeks, and divided into TEM-untreated and -treated rats. Seven control rats were injected with saline intraperitoneally. Body weight, hemodynamics, and echocardiographic measurements including quantitative analysis of ultrasonic integrated backscatter (IB) were obtained for 12 weeks after treatment. Finally, rats were killed for histopathologic study. At 6 weeks, end-diastolic left ventricular diameter (LVD) and percentage fractional shortening (%FS) were similar in TEM-treated and TEM-untreated rats, but cyclic variation of IB (dB) significantly decreased in TEM-untreated rats (7.3 +/- 1.2; control rats, 9.7 +/- 0.9; p < 0.01). At 12 weeks, %FS decreased in TEM-untreated rats (26.1 +/- 6.1%: TEM-treated rats, 34.2 +/- 6.2; p < 0.05), and calibrated IB (dB) in TEM-untreated rats (15.5 +/- 0.5) increased as compared with that in TEM-treated rats (12.1 +/- 0.7; p < 0.01). Interstitial collagen accumulation increased in TEM-untreated rats and was inhibited in treated rats. Simultaneous administration of TEM with doxorubicin was beneficial in preventing doxorubicin-induced myocardial damage, and myocardial tissue characterization was useful for the early detection of myocardial damage and the assessment of therapy.

Mucilage strongly binds aluminum but does not prevent roots from aluminum injury in Zea mays

Abstract: The possible role of mucilage in protecting roots from aluminum (Al) injury was investigated in Zea mays L. (cv. Golden Cross Bantam), focusing on binding of Al with mucilage and effects of mucilage on Al toxicity. Al was bound to mucilage after the treatment of roots with 10-50 μM Al for 1 h and 30 μM Al for 30, 60, 90 and 120 min. Using molecular sieve chromatography (Sephadex G-100), Al was co-eluted with a high molecular mass sugar and a low molecular mass sugar. The difficulty in desorbing Al from mucilage with organic acids confirmed the strong binding strength of Al by mucilage revealed by 27 Al nuclear magnetic resonance (NMR). Al could not be desorbed completely by succinic, malic, oxalic and citric acid at a molar ratio of 1:1. It could only be completely removed by oxalic acid at a molar ratio of 20:1 (oxalate:Al). Bioassay experiments showed that cell viability and callose formation were unaffected by Al bound to mucilage. However, mucilage deprived roots had only 0.21-0.59 nmol apex -1 higher Al content than control roots after treatment with 30 μM Al for 1, 1.5 and 2 h. Moreover, inhibition of root elongation by 5 μM Al for 6, 12, 24 and 36 h was independent of the presence or absence of mucilage prior to the Al treatment. These results indicate that although mucilage affects the accumulation of Al by roots, it does not confer Al resistance to Z. mays root apices.

Thermobaric structure of the Kokchetav ultrahigh-pressure-high-pressure massif deduced from a north-south transect in the Kulet and Saldat-Kol regions, northern Kazakhstan

Abstract: To investigate the regional thermobaric structure of the diamondiferous Kokchetav ultrahigh-pressure and high-pressure (UHP–HP) massif and adjacent units, eclogite and other metabasites in the Kulet and Saldat–Kol regions, northern Kazakhstan, were examined. The UHP–HP massif is subdivided into four units, bounded by subhorizontal faults. Unit I is situated at the lowest level of the massif and consists of garnet–amphibolite and acidic gneiss with minor pelitic schist and orthogneiss. Unit II, which structurally overlies Unit I, is composed mainly of pelitic schist and gneiss, and whiteschist locally with abundant eclogite blocks. The primary minerals observed in Kulet and Saldat–Kol eclogites are omphacite, sodic augite, garnet, quartz, rutile and minor barroisite, hornblende, zoisite, clinozoisite and phengite. Rare kyanite occurs as inclusions in garnet. Coesite inclusions occur in garnet porphyroblasts in whiteschist from Kulet, which are closely associated with eclogite masses. Unit III consists of alternating orthogneiss and amphibolite with local eclogite masses. The structurally highest unit, Unit IV, is composed of quartzitic schist with minor pelitic, calcareous, and basic schist intercalations. Mineral assemblages and compositions, and occurrences of polymorphs of SiO2 (quartz or coesite) in metabasites and associated rocks in the Kulet and Saldat–Kol regions indicate that the metamorphic grades correspond to epidote–amphibolite, through high-pressure amphibolite and quartz–eclogite, to coesite–eclogite facies conditions. Based on estimations by several geothermobarometers, eclogite from Unit II yielded the highest peak pressure and temperature conditions in the UHP–HP massif, with metamorphic pressure and temperature decreasing towards the upper and lower structural units. The observed thermobaric structure is subhorizontal. The UHP–HP massif is overlain by a weakly metamorphosed unit to the north and is underlain by the low-pressure Daulet Suite to the south; boundaries are subhorizontal faults. There is a distinct pressure gap across these boundaries. These suggest that the highest grade unit, Unit II, has been selectively extruded from the greatest depths within the UHP–HP unit during the exhumation process, and that all of the UHP–HP unit has been tectonically intruded and juxtaposed into the adjacent lower grade units at shallower depths of about 10 km.

The evolution of C4 plants: Acquisition of cis-regulatory sequences in the promoter of C4-type pyruvate, orthophosphate dikinase gene

Abstract: Summary In a previous study, we identified the C4-like pyruvate, orthophosphate dikinase gene (Pdk) in the C3 plant rice, with a similar structure to the C4-type Pdk in the C4 plant maize. In order to elucidate the differences between C4-type and C4-like Pdk genes in C4 and C3 plants, we have produced chimeric constructs with the β-glucuronidase (GUS) reporter gene under the control of the Pdk promoters. In transgenic rice, both rice and maize promoters directed GUS expression in photosynthetic organs in a light-dependent manner. However, the maize promoter exhibited a much higher transcriptional activity than the rice promoter did. These results indicate that the rice C4-like Pdk gene resembles the maize C4-type Pdk gene in terms of regulation of expression. We also tested the activity of the rice promoter in transgenic maize. GUS activity was seen in both photosynthetic and non-photosynthetic organs. Thus, the rice promoter does not confer a strict organ-specific gene expression, as the maize promoter does. Moreover, the rice promoter directed GUS expression not only in mesophyll cells but also in bundle sheath cells, whereas the maize promoter directed expression only in mesophyll cells. Taken together, the results obtained from both transgenic maize and rice demonstrate that the rice and maize promoters differ not only quantitatively, but also qualitatively, in terms of their cell- and organ-specificity. Experiments with swapped promoters using the rice and maize promoters further demonstrated that a limited sequence region from −330 to −76 of the maize promoter confers light-regulated, high-level expression to the rice promoter in maize mesophyll protoplasts. We conclude the gain of cis-acting elements conferring high-level expression and mesophyll cell specificity was necessary for establishment of a C4-type Pdk gene during the course of evolution from C3 to C4 plants.

Elevation of anti-cytokeratin 18 antibody and circulating cytokeratin 18: anti-cytokeratin 18 antibody immune complexes in sera of patients with idiopathic pulmonary fibrosis.

Abstract: In this study, we hypothesize that anti-cytokeratin 18 (CK18) antibody and CK18:anti-CK18 immune complex increase in sera in patients with idiopathic pulmonary fibrosis (IPF). To prove the existence of anti-CK18 antibodies in patients' sera, bovine CK18 was stained with patients' sera using a Western blotting. In patients with IPF, anti-CK18 antibodies were clearly demonstrated in sera by Western blotting. Then, we tried to establish an enzyme-linked immunosorbent assay (ELISA) to quantify anti-CK18 antibodies and CK18:anti-CK18 immune complexes in sera of patients with IPF. Levels of anti-human CK18 antibodies in sera of patients with IPF (0.81 ± 0.31, mean ± SD) measured by ELISA were significantly high compared with that of normal volunteers (0.45 ± 0.06, p < 0.01). In addition, levels of CK18:anti-CK18 antibody complexes in patients' sera (0.64 ± 0.35, man ± SD) significantly increased compared with those of normal subjects (0.40 ± 0.10, p < 0.01). These results suggest that anti-CK18 antibody and its immune complex may have played a role in the process of lung injury in IPF.

Clostridium perfringens iota-toxin requires activation of both binding and enzymatic components for cytopathic activity

Abstract: Iota-toxin is produced by Clostridium perfringens type E strains and consists of two independent components, the enzymatic and binding components, referred to as Ia and Ib, respectively. A recombinant C. perfringens strain, strain 667/pMRP147, produced processed Ia and partially processed Ib, while a recombinant C. perfringens type A strain, strain TS133/pMRP147, in which the VirR-VirS two-component system is inactivated, produced only precursor forms of Ia and Ib. This suggests that iota-toxin is processed by a VirR-VirS-responsive protease, although not completely in the recombinant type A strain. The precursor forms of Ia and Ib were purified from cultures of the latter strain, and their proteolytic activation was examined. Treatment with proteases cleaved off small peptides (9 to 13 amino acid residues) and a 20-kDa peptide from the N termini of the Ia and Ib precursors, respectively, leading to their active forms. They were activated efficiently by α-chymotrypsin, pepsin, proteinase K, subtilisin, and thermolysin but only weakly by trypsin, as demonstrated by the cell-rounding assay. λ-Protease from the C. perfringens type E strain, which was found to be a zinc-dependent protease related to thermolysin, activated iota-toxin as efficiently as did α-chymotrypsin. These results suggest that λ-protease is most responsible for the activation of iota-toxin in type E strains.

Evaluation of the importance of lactate for the activation of ethanolic fermentation in lettuce roots in anoxia

Abstract: According to the Davies–Roberts hypothesis, plants primarily respond to oxygen limitation by a burst of lactate production and the resulting pH drop in the cytoplasm activates ethanolic fermentation. To evaluate this system in lettuce (Lactuca sativa L.), seedlings were subjected to anoxia and in vitro activities of alcohol dehydrogenase (ADH, EC 1.1.1.1), pyruvate decarboxylase (PDC, EC 4.1.1.1) and lactate dehydrogenase (LDH, EC 1.1.1.27) and concentrations of ethanol, acetaldehyde and lactate were determined in roots of the seedlings. The in vitro activities of ADH and PDC in the roots increase in anoxia, whereas no significant increase was measured in LDH activity. At 6 h, the ADH and PDC activities in the roots kept in anoxia were 2.8- and 2.9-fold greater than those in air, respectively. Ethanol and acetaldehyde in the roots accumulated rapidly in anoxia and increased 8- and 4-fold compared with those in air by 6 h, respectively. However, lactate concentration did not increase and an initial burst of lactate production was not found. Thus, ethanol and acetaldehyde production occurred without an increase in lactate synthesis. Treatments with antimycin A and salicylhydroxamic acid, which are respiratory inhibitors, to the lettuce seedlings in the presence of oxygen increased the concentrations of ethanol and acetaldehyde but not of lactate. These results suggest that ethanolic fermentation may be activated without preceding activation of lactate fermentation and may be not regulated by oxygen concentration directly.

Transmission Electron Microscopic Demonstration of Phagocytosis and Intracellular Processing of Segmented Filamentous Bacteria by Intestinal Epithelial Cells of the Chick Ileum

Abstract: Segmented filamentous bacteria (SFB) are autochthonous bacteria colonizing the ileum of many young animals by attaching to intestinal epithelial cells These nonpathogenic bacteria strongly stimulate the mucosal immune system and induce intestinal epithelial cells to express major histocompatibility complex class II molecules We tried to discover whether SFB are phagocytized and intracellularly processed by the host cells, which is indicative of antigen processing The middle part of the ileum was extracted from 10- and 20-day-old broiler chicks (Gallus gallus domesticus) Samples were processed and examined by scanning and transmission electron microscopy (SEM and TEM, respectively) In SEM, no, few, medium, and dense SFB colonization levels were classified In TEM of cells from animals with medium or dense SFB colonization levels, we could observe extracellular particles ranging from those only indenting the cell membrane to particles found in the cytoplasmatic area beyond the terminal web These particles had a structural similarity with SFB that were floating freely in the intestinal lumen Furthermore, we observed unlacing of the membrane and septum surrounding the extracellular particles and their incorporation into host cytoplasmatic components, which strongly suggests that these particles are phagocytized and intracellularly processed SFB This conclusion is supported by TEM analysis of samples with no or few SFB, in which we failed to find these characteristic morphologies The phagocytosis process described here could be an important trigger for the stimulating effect of SFB on the mucosal immune system

Methodological Issues in Cross-Cultural Management Research: Problems, Solutions, and Proposals

Abstract: The research field of cross-cultural management suffers from an absence of theory capable of explaining the role of culture in organizational behavior. Methodological issues that are at least partly responsible for the above shortcoming are explored in this paper. The central argument is that, despite efforts to resolve these issues, many methodological problems continue to resist the remedies prescribed by researchers. This paper seeks to evaluate the reasons for this, and based on these evaluations, proposes some suggestions for future research.