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The LATERAL ORGAN BOUNDARIES (LOB) DOMAIN/ASYMMETRIC LEAVES2-LIKE (LBD/ASL) gene family members play key roles in diverse aspects of plant development. Previous studies have shown that LBD16, 18, 29 and 33 are critical for integrating the plant hormone auxin to control lateral root development in Arabidopsis thaliana. In the present study, we show that LBD14 is expressed exclusively in the root where it promotes lateral root (LR) emergence. Repression of LBD14 expression by ABA correlates with the inhibitory effects of ABA on LR emergence. Transient gene expression assays with Arabidopsis protoplasts demonstrated that LBD14 is a nuclear-localized transcriptional activator. The knock-down of LBD14 expression by RNA interference (RNAi) resulted in reduced LR formation by delaying both LR primordium development and LR emergence, whereas overexpression of LBD14 in Arabidopsis enhances LR formation. We show that ABA (but not other plant hormones such as auxin, brassinosteroids and cytokinin) specifically down-regulated β-glucuronidase (GUS) expression under the control of the LBD14 promoter in transgenic Arabidopsis during LR development from initiation to emergence and endogenous LBD14 transcript levels in the root. Moreover, RNAi of LBD14 enhanced the LR suppression in response to ABA, whereas LBD14 overexpression did not alter the ABA-mediated suppression of LR formation. Taken together, these results suggest that LBD14 promoting LR formation is one of the critical factors regulated by ABA to inhibit LR growth, contributing to the regulation of the Arabidopsis root system architecture in response to ABA.

Propane dehydrogenation in oxygen free environment over alumina-supported chromium oxide catalysts with different chromium loading was studied within short time-on-stream range for the fluidized moving bed applications. For this purpose, a series of CrOx/Al2O3 and CrOx/Zr-Al2O3 catalysts were prepared and examined. Increase in the chromium loading resulted in reduction of monochromate species, possibly leading to formation of polychromate species. Further increase of chromium loading led to formation of Cr2O3 species. Accordingly, specific activity of the catalyst decreased with increasing chromium loading. Propane conversion significantly decreased and propylene selectivity increased during an induction period due to the rapid consumption of limited lattice oxygen in the catalyst. Equilibrated and artificially-aged catalysts were characterized in order to investigate the factors affecting propylene selectivity and catalyst durability by pore analysis, temperature-programmed reduction (H2-TPR), temperature-programmed desorption (NH3-TPD), X-ray diffraction patterns (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). After an artificial catalyst aging treatment, all catalysts showed reduction in catalytic activity and the most drastic activity decrease was found in the catalyst with the highest loading of 20 wt% Cr/γ-Al2O3 sample. The activity loss was mainly due to agglomeration of the chromium species, reduction of the surface area, and transformation of Cr6+ species into stable Cr2O3 species. Cr species were agglomerated on the surface of alumina support during the aging treatment and the agglomeration was more pronounced at the high Cr loading. Moreover, Raman spectroscopy and XRD analyses revealed the formation of chromia/alumina solid solution in the catalyst after the aging treatment which also significantly contributed to the activity loss. Contrarily, Zr modified alumina support successfully suppressed the formation of chromia/alumina solid solution phase and substantially improved the catalytic activity after the aging treatment by increasing the dispersion of chromium oxide. Zr-Al2O3 support showed lower catalytic activity toward propylene than Al2O3 support, which also contributed to the higher propylene yield of Cr/Zr-Al2O3.

We successfully synthesized hydrothermally stable ZSM-5 with crystalline nano seeds. We employed a template-free method using ZSM-5 crystalline nano seeds and sodium silicate as a silica source. The prepared ZSM-5 exhibited uniform crystal size and relative crystallinity greater than 100 %. The size of the crystalline nano seed in the scale of 100 nm was found to be the optimum size for obtaining uniform, highly crystalline ZSM-5 with structural stability. After P-modification, the synthesized ZSM-5 with the optimally sized seed showed high hydrothermal stability and improved catalytic naphtha cracking activity compared to a commercial ZSM-5 catalyst. In order to find the elements for the increased hydrothermal stability, the samples were evaluated by studying crystallinity, aluminum spectrum, and acidity using XRD, solid-state NMR, and NH3-TPD, respectively after steaming at 800 °C for 24 h. It is speculated that the increased hydrothermal stability of the ZSM-5 resulted mainly from the increased aluminum structural stability.

For the development of a dry solid sorbent having quite fast CO2 sorption kinetics in an intermediate temperature range of 245–300 °C to be applicable to a riser-type fluidized bed carbonator, samples of Al2O3-supported MgCO3 (1.2 mmol/g) promoted with different molar amounts of Na2CO3 (1.2, 1.8 mmol/g) and/or NaNO3 (0.6 mmol/g) were prepared by incipient wetness pore volume impregnation. For a reference, an unsupported bulk phase sorbent of NaNO3-Na2Mg(CO3)2 was also prepared. From the sorption reaction using a gas mixture containing CO2 by 2.5–10% at 1 bar for the sorbents after their activation to MgO, Al2O3-supported sorbents were featured by their rapid carbonation kinetics in contrast to the unsupported sorbent showing a quite slow carbonation behavior. The addition of Na2CO3 to the MgCO3/Al2O3 sorbent made MgO species more reactive for the carbonation, bringing about a markedly enhanced kinetic rate and conversion, as compared with the unpromoted MgCO3/Al2O3 sorbent having a small negligible reactivity. The addition of NaNO3 to MgCO3/Al2O3 or to Na2CO3-MgCO3/Al2O3 induced the same promotional effects, but to a lesser magnitude, as observed for the Na2CO3 addition. It was also characteristic for all these MgCO3-based sorbents that initial carbonation conversions with time appeared as sigmoid curves. For the Al2O3-supported sorbent comprised of NaNO3, Na2CO3, and MgCO3 by 0.6, 1.8, and 1.2 mmols, respectively, per gram sorbent, showing the best kinetic performance, a kinetic equation capable of reflecting such sigmoid conversion behavior was established, and its applicability to a riser carbonator was examined throughout a simple model calculation based on the kinetics obtained.

Fully indium-exchanged zeolite Y, |In+62.6(In57+)1.2|[Si121Al71O384], was prepared by thallous ion exchange (TIE), a vapor phase ion exchange method. InCl(g, 510 Pa) was allowed to react with a single crystal of Tl71–Y under anhydrous conditions at 623 K. A second crystal prepared as above was washed with deionized water and redehydrated to give |In+39.7 (In57+)4.5|[Si121Al71O384]. The structures of fully dehydrated Tl71–Y and these two forms of In–Y were determined by single-crystal crystallography using synchrotron X-radiation. Then the two In–Y crystals were subjected to scanning electron microscopy energy-dispersive X-ray (SEM-EDX) analysis. Both methods indicated that no Tl remained in the In–Y crystals. The additional steps of washing and redehydration caused some of the In+ ions in the first In–Y crystal to disproportionate to give additional In57+ clusters in the sodalite cavities and In0 atoms on the crystal surface. Most of the In+ ions in both forms of In–Y are easily accessible to guest molecu...

CuO/Al 2 O 3 was used for dehydrogenation of butenes (1-butene, cis-2-butene, and trans-2-butene) to 1,3-butadiene at 200 °C under an anaerobic condition without an excessive amount of dilution. 1,3-butadiene was selectively obtained from butenes without the formation of carbon oxides over the CuO/Al 2 O 3 catalyst. Bifunctionality of oxidation and C−H bond activation by CuO and Al 2 O 3 , respectively, were strongly required for the selective conversion of the butenes to 1,3-butadiene.

The inter-conversion of light olefins over four types of HZSM-5 based catalysts under cracking conditions was investigated systematically and various methods including XRD, Ar adsorption–desorption, NH3-TPD, 27Al and 31P MAS–NMR were used to characterize the effects of P modification and steaming on ZSM-5. Regardless the types of catalyst, the same behaviors of light olefin inter-conversion were observed only depending on conversion of light olefins. Also, the conversion and selectivity were not influenced by the presence of hydrogen, suggesting that light paraffins were mainly produced from hydrogen transfer during cracking rather than hydrogenation of light olefins. It can be suggested that the inter-conversion of light olefins occurs through oligomerization of light olefins and then re-cracking of the oligomerized products. To guarantee high light olefin yield in catalytic naphtha cracking, it is strongly required to suppress oligomerization of light olefins during catalytic cracking.

For the kinetic study of K2CO3/ZrO2 sorbent in the carbonation reaction to capture CO2 from the flue gas, reaction experiments were carried out at temperatures between 328 and 343 K for CO2 gas compositions not exceeding 18% at 1 bar, and a phenomenological kinetic model was proposed to fit the carbonation conversion data obtained. Time-dependent carbonation conversions of the sorbent appeared as sigmoid curves. Sigmoid characteristics of the conversion curve were more pronounced for the sorption reaction at lower temperature and lower gas phase concentration of CO2. Such conversion behavior of fresh-dried K2CO3/ZrO2 sorbent could be closely described with the reaction rate equation in the form: r = kf(X)yCO2n . The reaction rate constant k as a temperature dependent term could be represented by Arrhenius’ equation with the negative apparent activation energy of −17.43 kJ/mol and the pre-exponential factor of 3.83 × 10–3 1/min. The term f(X) was a function introduced to reflect the carbonation rate change...

Hydrogenation of silicon tetrachloride (SiCl 4 ) to trichlorosilane (SiHCl 3 ) using carbon-based catalysts is studied. The results show that surface functional groups that result from the defect sites of the carbon catalysts play an important role in producing SiHCl 3 . Because the metal−carbon composites obtained by treating sucrose and transition metals at high temperature in the N 2 flow have more defect sites, they display an increased SiHCl 3 yield. Elemental analysis of the catalyst and reaction results demonstrate that there is a very good correlation between the SiHCl 3 yield and the amount of deposited silicon during the induction time, and the SiHCl 3 yield and the accumulated amount of deposited Si species rapidly change initially and then reach a stable value. Hydrogenation of SiCl 4 to SiHCl 3 in metal-grade silicon (mg−Si) powder is known to give a higher equilibrium conversion of SiCl 4 . In a similar way, by introducing Si powder into the catalyst bed, a higher SiHCl 3 yield can be obtained. It is important to retard the reverse reaction rate of HCl and SiHCl 3 to increase the SiHCl 3 yield; therefore, the HCl concentration in the product stream should be reduced as soon as it is formed on the catalyst surface during the hydrogenation of SiCl 4 . Consequently, the Si-doped metal−carbon composite catalyst shows a higher SiHCl 3 yield than that of the physically-mixed catalyst and mg−Si powder. These results offer a quite promising potential for developing a stable and effective SiCl 4 hydrogenation catalyst and can promote a deeper understanding of this important poly-Si industry reaction.

Cytokinin signaling in Arabidopsis thaliana utilizes a multi-step two-component signaling (TCS) system comprised of sensor histidine kinases (AHKs), histidine phosphotransfer proteins (AHPs), and response regulators (ARRs). Recent studies have suggested that the cytokinin TCS system is involved in a variety of other signaling and metabolic pathways. To further explore a potential function of the cytokinin TCS in the Arabidopsis dehydration stress response, we investigated the expression of all type-A ARR genes and a type-C ARR, ARR22, in both wild type and ahk single, double, and triple mutants in response to dehydration compared to cytokinin as well as dehydration tolerance of ahk mutants. We found that drought significantly induced the expression of a subset of ARR genes, ARR5, ARR7, ARR15, and ARR22. The results of expression analyses in ahk single, double, and triple mutants demonstrated that the cytokinin receptors AHK2 and AHK3 are redundantly involved in dehydration-inducible expression of ARR7, but not that of ARR5, ARR15, or ARR22. Dehydration tolerance assays showed that ahk2 and ahk3 single mutants exhibited enhanced dehydration tolerance compared with that of wild-type plants and ahk4 mutants, and that ahk2 ahk3 double mutants exhibited stronger drought tolerance than that of ahk3 ahk4, which exhibited more enhanced drought tolerance than that of wild-type plants and ahk single mutants. Taken together, these results demonstrate that while the cytokinin receptors AHK2 and AHK3 are critically involved in the dehydration tolerance response, both cytokinin receptor-dependent pathway and receptor-independent pathway occur in the dehydration response regulating ARR gene expression. In addition, preincubating ahk2, ahk3, ahk4, and the wild-type plants with cytokinin induced enhanced dehydration stress tolerance in these plants, demonstrating that cytokinins are involved in regulating plant response to dehydration stress.

The influences of steaming or washing treatment on P-modified HZSM-5 catalyst were investigated systematically in order for getting deep insight into the role of P species in catalytic cracking. The impregnation of P leads to better hydrothermal stability and higher yields of light olefin (ethylene and propylene), but brings rapid decrease of acidity. During steaming, the impregnated P species become more condensed phase and the acidity and catalytic activity decreased further. However, the acidity and catalytic cracking activity recovered just by washing with water even for steamed samples, suggesting that the existence of condensed P species blocks the pores of zeolite reversibly and are responsible for the decrease of cracking activity of naphtha.

A number of important chemicals are made from light olefins such as propylene and ethylene, and it is expected that market demand for these light olefins will continue to grow at 4–5% annually, and the average overall growth of propylene will be about 1% higher than that of ethylene. From the viewpoint of supply of feedstock and demand of light olefins, it is anticipated that the thermal cracking process of naphtha will be gradually transformed to a catalytic process such as ACOTM that can efficiently produce both ethylene and propylene in high yield. Also, together with primary light olefin production technologies utilizing heavy feedstocks such as DCCTM, and HPFCC, supplementary propylene production technologies utilizing C4–C4 such as SUPERFLEXTM, MOITM, and PROPYLURTM will be applied gradually in commercial production.

Micro-spherical Ni 0.80 Co 0.15 Mn 0.05 (OH) 2 precursors with a narrow size-distribution and high tap-density are prepared successfully by continuous co-precipitation of the corresponding metal salt solutions using NaOH and NH 4 OH as precipitation and complexing agents. LiNi 0.80 Co 0.15 Mn 0.05 O 2 is then prepared as a lithium battery cathode from this precursor by the introduction of LiOH·H 2 O. The pH and NH 3 :metal molar ratio show significant effects on the morphology, microstructure and tap-density of the prepared Ni 0.80 Co 0.15 Mn 0.05 (OH) 2 and the R values and I (0 0 3)/ I (1 0 4) ratio of lithiated LiNi 0.80 Co 0.15 Mn 0.05 O 2 . Spherical LiNi 0.80 Co 0.15 Mn 0.05 O 2 prepared under optimum conditions reveals a hexagonally ordered, layered structure without cation mixing and an initial charging capacity of 176 mAhg −1 . More than 91% of the capacity is retained after 40 cycles at the 1 C rate in a cut-off voltage range of 4.3–3.0 V.

Silicon- and Boron-modified H-BEA(Si/Al ratio of 12.5) were prepared by chemical liquid deposition (CLD) of tetraethyl orthosilicate (TEOS) and post-modification method using boric acid, respectively. The catalytic performance of the modified H-BEA catalysts was evaluated for the isomerization of 2,7-dimethyltetralin (DMT) to 2,6-DMT. It was found that the silylation with TEOS passivated preferentially the external acid sites of H-BEA zeolite while the Boron passivated both of the external and internal acid sites. The strong Bronsted acid sites were responsible for the side reactions such as dealkylation, cracking and transalkylation and can be prevented effectively by the silylation and boronation of BEA zeolite.

ZSM-5 was synthesized by template-free method using sodium silicate as a silica source and the content of Na2O in mother liquid was controlled by H2SO4. To see the effect of Na2SO4 generated by added H2SO4, hydrothermal crystallization was carried out with two types of mother liquids having low and high Na2SO4 contents at 170 C. The physical and chemical properties of ZSM-5s prepared in two different con- ditions were compared by XRD, EDS, FTIR, micropore analyzer and particle size analyzer. High crystalline, isometrical shaped and uniform 1-2 lm sized ZSM-5s with relative crystallinity around 100% could be obtained successfully from the mother liquids having the molar range of (11.0-21.0) Na2O:(21.4-11.4) Na2SO4:100.0 SiO2:2.0 Al2O3:4000.0 H2O. Through the crystallization in the absence and presence of extra Na2SO4, it was found that the condensation rate of aluminosilicate was increased by the Na2SO4 and resulted in the formation of amorphous phase instead of crystalline ZSM-5. The formation of crystalline HZSM-5 was prohibited critically if the total amount of Na2SO4 in mother liquid was higher than 24.4 mole based on 100.0 mole of SiO2. The enhanced condensation reaction and the preferential formation of agglomerated amorphous aluminosilicates in the presence of Na2SO4 could be explained by the oxy- anion effect of SO 2� 4 generated by Na2SO4.

The Arabidopsis thaliana secretome was analyzed by the proteomic approach, which led to the identification of secreted proteins implicated in many aspects of cell biology. We then investigated the change in the Arabidopsis secretome in response to salicylic acid and identified several proteins involved in pathogen response. One of these, a secreted lipase with a GDSL-like motif designated GDSL LIPASE1 (GLIP1), was further characterized for its function in disease resistance. glip1 plants were markedly more susceptible to infection by the necrotrophic fungus Alternaria brassicicola compared with the parental wild-type plants. The recombinant GLIP1 protein possessed lipase and antimicrobial activities that directly disrupt fungal spore integrity. Furthermore, GLIP1 appeared to trigger systemic resistance signaling in plants when challenged with A. brassicicola, because pretreatment of the glip1 mutant with recombinant GLIP1 protein inhibited A. brassicicola–induced cell death in both peripheral and distal leaves. Moreover, glip1 showed altered expression of defense- and ethylene-related genes. GLIP1 transcription was increased by ethephon, the ethylene releaser, but not by salicylic acid or jasmonic acid. These results suggest that GLIP1, in association with ethylene signaling, may be a critical component in plant resistance to A. brassicicola.

Selective production of 2,6-dimethylnaphthalene (2,6-DMN) from 2,7-rich DMN has been investigated, with one-step and successive three-step isomerization containing (i) hydrogenation of 2,7-rich DMN to 2,7-rich dimethyl tetralin, (ii) isomerization of 2,7-rich DMT to 2,6-rich DMT, and (iii) dehydrogenation of 2,6-rich DMT into 2,6-rich DMN, respectively. It was found that the intra-triad isomerization of DMN was possible even at 200 °C, but for the inter-triad isomerization at least 250 °C was required. If the reaction temperature is higher than 300 °C, the yield of 2,6-DMN decreases rapidly due to the side reactions such as dealkylation, cracking and transalkylation. It was also found that 2,6-DMN or 2,6-DMT selectivity were strongly dependant on the Si/Al ratio of H-BEA (or the Bronsted site) and the maximum yield of 2,6-DMN (or 2,6-DMT) was obtained at the Si/Al ratio of 12.5. In the case of DMT, inter- and intra-triads did not show difference in isomerization temperature and were possible even at 180 °C. 14.9% yield of 2,6-DMT was obtained through the three-step isomerization over H-BEA(12.5) at 200 °C, while 10% yield of 2,6-DMN was achieved by one-step isomerization over H-BEA(12.5) at 250 °C.

Summary 1. Heavy alcohol consumption has been known as a risk factor for hypertension, although the mechanism by which alcohol intake causes hypertension remains elusive. 2. We tested the hypothesis that brief exposure to ethanol augments vascular contractility through the stress response in human chorionic plate arteries. 3. Human chorionic plate arteries were mounted in organ baths and exposed to 5% ethanol for 15, 30 or 45 min. 4. Brief exposure for 45 min, but not 15 min, not only augmented contractility to KCl and 5-hydroxytryptamine 5 h after the end of exposure, but also increased the expression of heat shock protein (HSP) 70 in the tissues. 5. Reverse transcription–polymerase chain reaction showed gradual increases of hsp70 mRNA expression, but not heat shock cognate 70 (hsc70), hsp90α or glucose regulatory protein 78 (grp78) mRNA expression, in an exposure time-dependent manner 3 h after the end of exposure. 6. These results indicate that ethanol augments vascular contractility through the stress response.

The gene encoding Schwanniomyces occidentalis α-amylase (AMY) was introduced into the chromosomal δ sequences of an industrial strain of Saccharomyces cerevisiae. To obtain a strain suitable for commercial use, an δ-integrative cassette devoid of bacterial DNA sequences was constructed that contains the AMY gene and aureobasidin A resistance gene (AUR1-C) as the selection marker. The AMY gene was expressed under the control of the alcohol dehydrogenase gene promoter (ADC1p). The α-amylase activity of Sacc. cerevisiae transformed with this integrative cassette was 6 times higher than that of Sch. occidentalis. The transformants (integrants) were mitotically stable after 100 generations in nonselective medium.

The developmental process of lateral root formation consists of priming, initiation, primordium development and the emergence of lateral roots from the primary root. Molecular genetic studies with Arabidopsis have revealed several key transcriptional regulators involved in lateral root development. However, their functional interaction has not been fully characterized yet. Here we utilized a genetic approach to understand some of these interactions, revealing that PUCHI functioning in morphogenesis of early lateral root primordium is regulated downstream of ARF7 / ARF19 and acts with LBD16 (ASL18)/ LBD18 (ASL20) to regulate lateral root development. We showed that auxin-responsive expression of PUCHI was significantly reduced in arf7 or arf19 single mutants and completely abolished in arf7 arf19 double mutants. Consistent with this, β-glucuronidase (GUS) expression under the PUCHI promoter in arf7 arf19 was greatly reduced in the lateral root primordium compared with that in the wild type and did not respond to exogenous auxin. Results of GUS expression analyses under the PUCHI , LBD16 or LBD18 promoter in lbd16 , lbd18 single and double mutants or puchi demonstrated that PUCHI and LBD16 or LBD18 do not regulate each other’s expression. Lateral root phenotypes of double and triple mutants of lbd16 , lbd18 and puchi showed that the puchi mutation in lbd16 and lbd18 mutants synergistically decreased the number of emerged lateral roots. These analyses also showed that puchi affected lateral root primordium development of lbd16 or lbd18 additively but differentially. Taken together, these results suggest that PUCHI co-acts with LBD16 and LBD18 to control lateral root primordium development and lateral root emergence.

The Arabidopsis two-component signaling system, which is comprised of sensor histidine kinases, histidine phosphotransfer proteins, and response regulators, mediates cytokinin response as well as various other plant responses including abiotic stress responses. Arabidopsis response regulators (ARRs) are classified into type-A, -B, and -C. Although the roles of type-A and -B ARRs are well established in Arabidopsis plant signaling, roles of type-C ARRs, ARR22 and ARR24, remain elusive. ARR22, a preferentially cytosolic protein, interacts with certain Arabidopsis histidine phosphotransfer proteins (AHPs) and displays phosphatase activity on AHP5. ARR22 is induced by cold and dehydration. Here, we show that inducible overexpression of ARR22 in Arabidopsis enhanced dehydration, drought, and cold tolerance in a dexamethasone-dependent manner, whereas mutation of the putative phospho-accepting Asp to Asn in ARR22 (ARR22(D74N)) abolished these tolerance phenotypes. Overexpression of ARR22 decreased electrolyte leakage in dehydration-, drought-, or cold-stressed transgenic Arabidopsis plants compared with that of ARR22(D74N) or compared with wild-type plants. Transpiration rates and stomatal apertures were not affected by ARR22 overexpression. No significant difference in both dehydration and freezing tolerance was observed between wild-type and arr22 mutants with or without cytokinin preincubation, consistent with the lack of phenotypes of arr22 mutants in their vegetative development. Meta-profile analyses of the microarray data on ARR22-responsive genes indicate that ARR22 modulates expression of a variety of abiotic stress-responsive genes, which might contribute to increasing drought and freezing tolerance. Taken together, these results suggest that ARR22 plays a positive role in the stress tolerance response in part via enhancing cell membrane integrity and that phospho-histidine phosphatase activity of ARR22 may be required for this function.

A multistep two-component signaling system is established as a key element of cytokinin signaling in Arabidopsis. Here, we provide evidence for a function of the two-component signaling system in cold stress response in Arabidopsis. Cold significantly induced the expression of a subset of A-type ARR genes and of GUS in Pro(ARR7):GUS transgenic Arabidopsis. AHK2 and AHK3 were found to be primarily involved in mediating cold to express A-type ARRs despite cytokinin deficiency. Cold neither significantly induced AHK2 and AHK3 expression nor altered the cytokinin contents of wild type within the 4 h during which the A-type ARR genes exhibited peak expression in response to cold, indicating that cold might induce ARR expression via the AHK2 and AHK3 proteins without alterations in cytokinin levels. The ahk2 ahk3 and ahk3 ahk4 mutants exhibited enhanced freezing tolerance compared with wild type. These ahk double mutants acclimated as efficiently to cold as did wild type. The overexpression of the cold-inducible ARR7 in Arabidopsis resulted in a hypersensitivity response to freezing temperatures under cold-acclimated conditions. The expression of C-repeat/dehydration-responsive element target genes was not affected by ARR7 overexpression as well as in ahk double mutants. By contrast, the arr7 mutants showed increased freezing tolerance. The ahk2 ahk3 and arr7 mutants showed hypersensitive response to abscisic acid (ABA) for germination, whereas ARR7 overexpression lines exhibited insensitive response to ABA. These results suggest that AHK2 and AHK3 and the cold-inducible A-type ARRs play a negative regulatory role in cold stress signaling via inhibition of ABA response, occurring independently of the cold acclimation pathway.

Background and Objectives：The myogenic response was originally described as a contraction of a blood vessel that occurred following an increase in intravascular distending pressure. Conversely, a reduction in intravascular pressure produces myogenic vascular relaxation. Recent attention has focused on the potential role of this myogenic mechanism in the control of tone in the resistance vasculature, and in particular on how this mechanism may contribute to the increased vascular resistance seen in hypertension. Therefore, in the present study, we investigated the role of myogenic tone in the generation and/or maintenance of hypertension. Materials and Methods：Myogenic tone was developed by stretching of the basilar arteries of WKY (Wistar Kyoto rat and SHR (spontaneously hypertensive rats. Contractile responses, PKC (protein kinase C immunoblots and translocation of PKC and RhoA were measured. Results：In the presence of extracellular Ca 2 ＋ , the stretching of the resting vessel evoked a myogenic contraction in the basilar arteries of SHR and WKY. Myogenic tone was significantly greater in SHR than in WKY. However, in the absence of extracellular Ca 2 ＋ , stretching evoked a myogenic contraction in SHR, but not in WKY. The stretch-induced myogenic tone was inhibited by nifedipine. The effect of nifedipine was similar in both SHR and WKY rats. H-7, calphostin C and Y-27632, also inhibited stretch-induced myogenic tone in both SHR and WKY. The inhibitory effects of these drugs were greater in SHR than in WKY. Immunoblotting showed rho A and PKCα were translocated from the cytosol to the cell membrane with stretching in both SHR and WKY. PKCe, however, was translocated to the cell membrane with stretching in SHR, but not in WKY. Conclusion：These results suggest that stretch-induced myogenic tone is significantly greater in SHR than in WKY. Furthermore, the increase in amount and/or activity of PKCe and ROK (rhoA-associated kinase may be a key mechanism accounting for the enhanced myogenic tone in SHR. (Korean Circulation J 2002;32(3 :257-267