Control of plant growth and development by overexpressing MAP3K17, an ABA-inducible MAP3K, in Arabidopsis

Abscisic acid (ABA) plays an important role in plant growth, development, and stress responses. ABA regulates many aspects of plant growth and development, including seed maturation, dormancy, germination, the transition from vegetative to reproductive growth, leaf senescence and responses to environmental stresses, such as drought, high salinity and cold. It is also known that mitogen-activated protein kinase (MAPK) cascades function in ABA signaling. Recently, we and another group have identified the ABA-inducible MAP3Ks MAP3K17 and MAP3K18 as the upstream MAP3Ks of MKK3, implicating the MAP3K17/18-MKK3-MPK1/2/7/14 cascade in ABA signaling. It has also been reported that overexpression of MAP3K18 in Arabidopsis causes an early leaf senescence phenotype, ABA hypersensitive stomata closing, and drought tolerance. In this study, we generated transgenic plants overexpressing MAP3K17 (35S:MAP3K17) and its kinase-inactive form (35S:MAP3K17KN). The bolting of 35S:MAP3K17 was earlier than WT, and the fresh weights of the seedlings were smaller, whereas 35S:MAP3K17KN showed the opposite phenotype. These results indicate that the transition from vegetative to reproductive growth can be regulated by overexpression of MAP3K17 and its kinase-inactive form. Moreover, 35S:MAP3K17 showed lower sensitivity to ABA during post-germinated growth, whereas 35S:MAP3K17 KN showed the opposite phenotype, suggesting the negative roles of MAP3K17 in the response to ABA. Our work provides the possibility to regulate plant growth and development by the genetic manipulation of ABA-induced MAPK cascades, leading to improved crop growth and productivity.

Growth stimulation in inflorescences of an Arabidopsis tubulin mutant under microgravity conditions in space

Cortical microtubules are involved in plant resistance to hypergravity, but their roles in resistance to 1 g gravity are still uncertain. To clarify this point, we cultivated an Arabidopsis α-tubulin 6 mutant (tua6) in the Cell Biology Experiment Facility on the Kibo Module of the International Space Station, and analyzed growth and cell wall mechanical properties of inflorescences. Growth of inflorescence stems was stimulated under microgravity conditions, as compared with ground and on-orbit 1 g conditions. The stems were 10-45% longer and their growth rate 15-55% higher under microgravity conditions than those under both 1 g conditions. The degree of growth stimulation tended to be higher in the tua6 mutant than the wild-type Columbia. Under microgravity conditions, the cell wall extensibility in elongating regions of inflorescences was significantly higher than the controls, suggesting that growth stimulation was caused by cell wall modifications. No clear differences were detected in any growth or cell wall property between ground and on-orbit 1 g controls. These results support the hypothesis that cortical microtubules generally play an important role in plant resistance to the gravitational force.

Wavefront analysis and ultrastructural findings in an eye with posterior lentiglobus

An 8-year-old girl with unilateral posterior lenticoglobus underwent lens aspiration and intraocular lens implantation. Wavefront analysis performed before surgery to assess the surgical indication showed a higher-order aberration of 0.502 μm root mean square. After surgery, the value decreased to 0.132 μm root mean square. Preoperative best-corrected visual acuity of 0.1 improved to 0.3 postoperatively. Electron-microscopic examinations of the posterior capsule revealed unusual nodular structures and variations in capsular density.

Modification of neodymium-doped ZnO hybrid nanoparticles under mild hydrothermal conditions

The morphology and particle size of neodymium-doped ZnO hybrid nanoparticles were tailored through fabrication under mild hydrothermal conditions (T = 150-250 degrees C, P = autogeneous, t = 18 h) for the first time using two surface modifiers: caprylic acid and n-butylamine. Characterization of these nanoparticles was carried out using powder XRD, FTIR, SEM, zeta-potential analysis and UV-vis spectroscopy. The results revealed that modification of ZnO nanoparticles using neodymium as a dopant and caprylic acid or n-butylamine as a surfactant could change the optical and physical properties of the surface-modified neodymium-doped ZnO hybrid nanoparticles. The work proved the efficiency of caprylic acid and n-butylamine as suitable surfactants for surface modification of neodymium-doped ZnO hybrid nanoparticles.

Marginal crack after intravitreal bevacizumab for myopic choroidal neovascularization

PURPOSE

To report new indocyanine green angiographic (ICGA) findings after intravitreal bevacizumab (IVB) for myopic choroidal neovascularization (mCNV).

CASES REPORT

Three eyes of three patients with mCNV were examined with fluorescein angiography (FA) and ICGA using Heidelberg Retinal Angiograph 2 and the conventional fundus camera before and after IVB. The cessation of angiographic leakage on FA was achieved in all eyes (100%) after IVB, however the hypofluorescent line delineating the margin of the neovascular tissue appeared in ICGA seemingly according to the contraction of mCNV. It was not detected either on FA or ICGA with the conventional camera. This hypofluorescence line enlarged over the time.

CONCLUSION

The contraction-associated hypofluorescence line, namely marginal crack line, indicates the early damage of retinal pigment epithelium and seems to lead to expanding macular chorioretinal atrophy typically seen in mCNV.

Outer retinal folds in highly myopic macular hole and retinal detachment

PURPOSE

To report the intraretinal microstructure in macular hole and retinal detachment in a highly myopic eye using spectral-domain optical coherence tomography.

METHODS

Two eyes of two patients with macular holes and retinal detachment were examined with spectral-domain optical coherence tomography. Fundus photographs and time-domain optical coherence tomography images also were obtained.

RESULTS

Spectral-domain optical coherence tomography disclosed outer retinal fold formation toward the subretinal space at the level of the photoreceptor inner and outer segment layer, the cystoid spaces expanding outside of the macular hole and epiretinal membrane in all eyes.

CONCLUSION

The outer retinal fold may indicate the tension of the inner retina and the redundancy of the outer retina, which may be responsible for the occurrence of macular holes and retinal detachment in these eyes.

Fundus autofluorescence related to retinal morphological and functional changes in idiopathic macular holes

PURPOSE

To investigate fundus autofluorescence (FAF) characteristics in relation to morphological and functional features of idiopathic macular hole (IMH).

METHODS

Twenty eyes of 20 consecutive patients with stage 3 or 4 macular holes were included. Fundus autofluorescence images were obtained using the Heidelberg retina angiograph 2, retinal structure was evaluated with 3-dimensional (3-D) imaging of Fourier-domain optical coherence tomography (FD-OCT), and retinal function was assessed with microperimetry-1 (MP-1).

RESULTS

Markedly increased FAF in the foveal centre corresponding to the macular hole, confirmed with FD-OCT, was demonstrated in all eyes. A surrounding hypoautofluorescent ring corresponded to the subretinal fluid cuff. The area of relatively reduced FAF around the ring corresponded precisely to retinal oedema. In 15 eyes (75%), a stellate appearance with dark radiating striae was seen in the relatively reduced FAF and was correlated with intraretinal cystic changes in the outer plexiform layer, observed by FD-OCT. Mean preoperative visual acuity was significantly poorer in eyes without a stellate appearance than in those with a stellate appearance (p = 0.023). The MP-1 study confirmed impaired retinal function in the macular hole bed and in the area of the fluid cuff and retinal oedema.

CONCLUSIONS

Fundus autofluorescence imaging reflects anatomic changes and represents the dysfunctional retinal area in IMH. The technique provides 2-D images with 3-D information on the retinal morphology of this disease.

Residual indocyanine green fluorescence pattern after vitrectomy with internal limiting membrane peeling in high myopia

PURPOSE

The use of indocyanine green (ICG) during intraoperative internal limiting membrane (ILM) peeling is common for various macular diseases. The authors observed residual ICG after vitrectomy for high myopia-related macular diseases and found a unique pattern specific to its pathologic features.

DESIGN

Observational case series.

METHODS

Twelve eyes of 12 patients with high myopia who had undergone vitrectomy with ICG-assisted ILM peeling were included (macular hole [MH], six eyes; MH and retinal detachment, three eyes; and myopic foveoschisis, three eyes). Patterns of residual ICG were observed in the posterior retina using the Heidelberg Retina Angiograph 2 (Heidelberg Engineering, Heidelberg, Germany) after surgery and were compared. The minimum follow-up was six months. Two control eyes of two patients without intravitreal ICG also were included in this study.

RESULTS

The residual ICG fluorescence was observed in all eyes except for the control eyes. The pattern of residual ICG fluorescence depended on the degree of myopic chorioretinal atrophy. In eyes with no or minimum chorioretinal atrophy, the pattern was similar to that of an idiopathic MH. The ICG pattern was unique in those with moderate or severe atrophy. A strong ICG signal was observed at the area of diffuse atrophy and at the edge of the patchy atrophy and staphyloma. No ICG fluorescence was observed inside the patchy atrophy.

CONCLUSIONS

Residual ICG fluorescence was observed in high myopia. ICG accumulation seems to depend on the status of the retinal pigment epithelial (RPE) underlying the posterior retina. RPE cells may play an important role in the kinetics of the residual ICG.

Residual indocyanine green fluorescence pattern after vitrectomy for idiopathic macular hole with internal limiting membrane peeling

BACKGROUND

Internal limiting membrane (ILM) peeling with indocyanine green (ICG) staining is a commonly used procedure to treat idiopathic macular holes (MH).

AIM

To report changes in the patterns of residual ICG fluorescence over time after vitrectomy using the Heidelberg Retina Angiograph 2 (HRA2, Heidelberg Engineering, Heidelberg, Germany).

METHODS

10 patients (10 eyes) who had undergone vitrectomy for MH with ILM peeling were included. 9 (90%) patients underwent ILM peeling with ICG, and 1 (10%) patient had it with triamcinolone acetonide (TA). We observed residual ICG using HRA2, postoperatively. Autofluorescence, optical coherence tomography images and best-corrected visual acuity (BCVA) measurements were also obtained. The minimal follow-up was 3 months.

RESULTS

The MHs were closed postoperatively in all patients (100%). In eyes that underwent ILM peeling with ICG, the BCVA improved significantly (p<0.001) in 8 (89%) eyes and was unchanged in 1 (11%) eye. HRA2 showed the ICG fluorescence patterns but not TA postoperatively. The ICG hyperfluorescent signal was typically diffuse at the posterior retina and was hypofluorescent around the fovea. The hyperfluorescence then migrated towards the optic nerve disc presumably along the nerve fibre, and the area of ILM peeling was clearly identified. A large number of hyperfluorescent dots were observed instead of diffuse hyperfluorescence that was observed just after surgery.

CONCLUSIONS

Patterns of residual ICG fluorescence were sequentially observed with HRA2 after vitrectomy for MH with ICG-assisted ILM peeling.

Effect of interferon on incidence of hepatocellular carcinoma in patients with chronic hepatitis C

BACKGROUND/AIMS

The aim of this study was to evaluate whether IFN prevents the development of HCC in patients with chronic hepatitis C.

METHODOLOGY

103 patients with chronic hepatitis C received IFN and 30 control patients were enrolled in this study.

RESULTS

In 33 patients (32.0%) who received IFN, alanine aminotransferase (ALT) decreased to normal range and HCV RNA became negative (complete response: CR). In 7 patients (6.7%), ALT decreased to less than 50 IU/L or stayed within the normal range, but HCV RNA remained positive (biochemical response: BR). In 63 patients (61.1%) and 30 control patients, ALT did not change and HCV RNA remained positive (no response: NR). HCC developed in 5 (4.9%) of the 103 patients who received IFN and 7 (23.3%) of the control patients (p<0.01). In 5 patients who developed HCC, the response to IFN was NR and no HCC developed in patients with CR or BR. In addition, 5-year cumulative rate of development of HCC in 63 IFN NR patients and in control was 7.9% and 23.3% (p<0.05).

CONCLUSIONS

IFN decreased the development of HCC in not only patients with CR or BR but also patients with NR.

Two-dimensional laboratory simulation of LNAPL infiltration and redistribution in the vadose zone

A quantitative two-dimensional laboratory experiment was conducted to investigate the immiscible flow of a light non-aqueous phase liquid (LNAPL) in the vadose zone. An image analysis technique was used to determine the two-dimensional saturation distribution of LNAPL, water and air during LNAPL infiltration and redistribution. Vertical water saturation variations were also continuously monitored with miniature resistivity probes. LNAPL and water pressures were measured using hydrophobic and hydrophilic tensiometers. This study is limited to homogeneous geological conditions, but the unique experimental methods developed will be used to examine more complex systems. The pressure measurements and the quantification of the saturation distribution of all the fluids in the entire flow domain under transient conditions provide quantitative data essential for testing the predictive capability of numerical models. The data are used to examine the adequacy of the constitutive pressure-saturation relations that are used in multiphase flow models. The results indicate that refinement of these commonly used hydraulic relations is needed for accurate model prediction. It is noted in particular that, in three-fluid phase systems, models should account for the existence of a residual NAPL saturation occurring after NAPL drainage. This is of notable importance because residual NAPL can act as a non negligible persistent source of contamination.

A review of NAPL source zone remediation efficiency and the mass flux approach

A number of previous studies are reviewed to examine the actual reduction of NAPL from source zones and the effectiveness of the specific technique of remediation used at sites under study. It has been shown that complete removal of the NAPL in free phase or residual is not possible due to the complex entrapment architecture of NAPLs at field sites. Consequently, the assessment of remediation efficiency should not be solely based on the reduction of entrapped NAPL mass from source zone. Instead, it should be based on the reduction of risk achieved through the lowering of the concentration of the dissolved constituents emanating from the entrapped NAPL during source zone clean-up. The prediction of the concentration in the plume requires a knowledge of the dissolution of NAPLs in the source zone. Attention is directed to the need for the understanding the mass transfer from entrapped NAPLs in the source zone before and after remediation. In this paper, the current knowledge of mass transfer processes from the non-aqueous phase to the aqueous phase is summarised and the use of mass flux measurements (monitoring the concentration of contaminants in aqueous phase due to source zone NAPL-groundwater mass transfer) is introduced as a potential tool to assess the efficiency of technologies used in source zone remediation. Preliminary results of numerical simulations reveal that factors such as source zone morphology as determined by the heterogeneity of the formation control the post-remediation dissolution behaviour, than the local mass transfer. Thus, accurate site characterization is essential for predicting NAPL dissolution and mass flux relationships as well as for assigning site-specific remediation target values.

Effect of NAPL entrapment conditions on air sparging remediation efficiency

The effect of soil heterogeneity and the entrapment condition of NAPL source on the mass removal efficiency of air sparging coupled with soil vapour extraction (AS/SVE) was investigated using an intermediate scale two-dimensional laboratory soil tank. Four different NAPL entrapments were created by varying the height of the water table in heterogeneous soil models. Different mass removal efficiencies were achieved for different NAPL entrapment conditions, which were governed by soil heterogeneity and water table height before and during AS/SVE operation. Remobilization and redistribution of toluene and water improved the mass removal. Overall results suggested that it was difficult to achieve the complete remediation of NAPL source due to complex entrapment in heterogeneous soil system. In order to assess the potential contamination in the post-remediation stage, gas and dissolved concentrations of toluene were measured after the AS/SVE operation. The results showed that gas concentration close to remaining NAPL source zone increased rapidly and reached to steady state values, which were much smaller than the vapour pressure, whereas the aqueous phase concentrations increased continuously toward the solubility limit.

Growth restoration in azuki bean and maize seedlings by removal of hypergravity stimuli

Hypergravity stimuli, gravitational acceleration of more than 1 x g, decrease the growth rate of azuki bean epicotyls and maize coleoptiles and mesocotyls by decreasing the cell wall extensibility via an increase in the molecular mass of matrix polysaccharides. An increase in the pH in the apoplastic fluid is hypothesized to be involved in the processes of the increase in the molecular mass of matrix polysaccharides due to hypergravity. However, whether such physiological changes by hypergravity are induced by normal physiological responses or caused by physiological damages have not been elucidated. In the present study, we examined the effects of the removal of hypergravity stimuli on growth and the cell wall properties of azuki bean and maize seedlings to clarify whether the effects of hypergravity stimuli on growth and the cell wall properties are reversible or irreversible. When the seedlings grown under hypergravity conditions at 300 x g for several hours were transferred to 1 x g conditions, the growth rate of azuki bean epicotyls and maize coleoptiles and mesocotyls greatly increased within a few hours. The recovery of growth rate of these organs was accompanied by an immediate increase in the cell wall extensibility, a decrease in the molecular mass of matrix polysaccharides, and an increase in matrix polysaccharide-degrading activities. The apoplastic pH also decreased promptly upon the removal of hypergravity stimuli. These results suggest that plants regulate the growth rate of shoots reversibly in response to hypergravity stimuli by changing the cell wall properties, by which they adapt themselves to different gravity conditions. This study also revealed that changes in growth and the cell wall properties under hypergravity conditions could be recognized as normal physiological responses of plants. In addition, the results suggest that the effects of microgravity on plant growth and cell wall properties should be reversible and could disappear promptly when plants are transferred from microgravity to 1 x g. Therefore, plant materials should be fixed or frozen on orbit for detecting microgravity-induced changes in physiological parameters after recovering the materials to earth in space experiments.

Hypergravity-induced changes in gene expression in Arabidopsis hypocotyls

Under hypergravity conditions, the cell wall of stem organs becomes mechanically rigid and elongation growth is suppressed, which can be recognized as the mechanism for plants to resist gravitational force. The changes in gene expression by hypergravity treatment were analyzed in Arabidopsis hypocotyls by the differential display method, for identifying genes involved in hypergravity-induced growth suppression. Sixty-two cDNA clones were expressed differentially between the control and 300 g conditions: the expression levels of 39 clones increased, whereas those of 23 clones decreased under hypergravity conditions. Sequence analysis and database searching revealed that 12 clones, 9 up-regulated and 3 down-regulated, have homology to known proteins. The expression of these genes was further analyzed using RT-PCR. Finally, six genes were confirmed to be up-regulated by hypergravity. One of such genes encoded 3-hydroxy-3-methylglutaryl-Coenzyme A reductase (HMGR), which catalyzes a reaction producing mevalonic acid, a key precursor of terpenoids such as membrane sterols and several types of hormones. The expression of HMGR gene increased within several hours after hypergravity treatment. Also, compactin, an inhibitor of HMGR, prevented hypergravity-induced growth suppression, suggesting that HMGR is involved in suppression of Arabidopsis hypocotyl growth by hypergravity. In addition, hypergravity increased the expression levels of genes encoding CCR1 and ERD15, which were shown to take part in the signaling pathway of environmental stimuli such as temperature and water, and those of the alpha-tubulin gene. These genes may be involved in a series of cellular events leading to growth suppression of stem organs under hypergravity conditions.

Effects of source zone heterogeneity on surfactant-enhanced NAPL dissolution and resulting remediation end-points

The effectiveness of removal of nonaqueous phase liquids (NAPLs) from the entrapment source zone of the subsurface has been limited by soil heterogeneity and the inability to locate all entrapped sources. The goal of this study was to demonstrate the uncertainty of degree of source removal associated with aquifer heterogeneity. In this demonstration, source zone NAPL removal using surfactant-enhanced dissolution was considered. Model components that simulate the processes of natural dissolution in aqueous phase and surfactant-enhanced dissolution were incorporated into an existing code of contaminant transport. The dissolution modules of the simulator used previously developed Gilland-Sherwood type phenomenological models of NAPL dissolution to estimate mass transfer coefficients that are upscaleable to multidimensional flow conditions found at field sites. The model was used to simulate the mass removal from 10 NAPL entrapment zone configurations based on previously conducted two-dimensional tank experiments. These entrapment zones represent the NAPL distribution in spatially correlated random fields of aquifer hydraulic conductivity. The numerical simulations representing two-dimensional conditions show that effectiveness of mass removal depends on the aquifer heterogeneity that controls the NAPL entrapment and delivery of the surfactant to the locations of entrapped NAPLs. Flow bypassing resulting from heterogeneity and the reduction of relative permeability due to NAPL entrapment reduces the delivery efficiency of the surfactant, thus prolonging the remediation time to achieve desired end-point NAPL saturations and downstream dissolved concentrations. In some extreme cases, the injected surfactant completely bypassed the NAPL source zones. It was also found that mass depletion rates for different NAPL source configurations vary significantly. The study shows that heterogeneity result in uncertainties in the mass removal and achievable end-points that are directly related to dissolved contaminant plume development downstream of the NAPL entrapment zone.

Hypergravity-induced increase in the apoplastic pH and its possible involvement in suppression of beta-glucan breakdown in maize seedlings

Elongation growth of both coleoptiles and mesocotyls of maize (Zea mays L. cv. Cross Bantam T51) seedlings was inhibited under basipetal hypergravity (300 g) conditions. Hypergravity increased the pH of the apoplastic fluid of coleoptiles from 5.0 to 5.5 and mesocotyls from 5.2 to 5.7. When beta-1,3:1,4-D-glucanases (beta-glucanases) extracted from cell walls of the 1-g control coleoptiles and mesocotyls were assayed at pH 5.0 and 5.5 for coleoptiles, and at 5.2 and 5.7 for mesocotyls, respectively, the activity in the increased pH conditions was significantly lower than that in the control pH conditions. During the autolysis of the enzymically active cell wall preparations obtained from 1-g control organs, a molecular mass downshift of hemicellulosic polysaccharides occurred in cell walls. This downshift was suppressed in the increased pH conditions as compared with the control pH conditions. It was reported that hypergravity increased the molecular mass of hemicellulosic polysaccharides by decreasing the beta-glucanase activity, and thereby decreased the mechanical extensibility of cell walls in maize coleoptiles and mesocotyls. These results suggest that, in maize coleoptiles and mesocotyls, hypergravity-induced increase in the pH in the apoplastic fluid is involved in the reduction of the activity of beta-glucanases which, in turn, causes an increase in the molecular mass of hemicellulosic polysaccharides and inhibits elongation growth.

Gravitational force regulates elongation growth of Arabidopsis hypocotyls by modifying xyloglucan metabolism

Growth of dark-grown Arabidopsis hypocotyls was suppressed under hypergravity conditions (300 g), or was stimulated under microgravity conditions in space (Space Shuttle STS-95). The mechanical extensibility of cell walls decreased and increased under hypergravity and microgravity conditions, respectively. The amounts of cell wall polysaccharides (pectin, hemicellulose-I, hemicellulose-II and cellulose) per unit length of hypocotyls increased under hypergravity conditions, and decreased under microgravity conditions. The amount and the molecular mass of xyloglucans also increased under the hypergravity conditions, while those decreased under microgravity conditions. The activity of xyloglucan-degrading enzymes extracted from hypocotyl cell walls decreased and increased under hypergravity and microgravity conditions, respectively. These results indicate that the amount and the molecular mass of xyloglucans are affected by the magnitude of gravity and that such changes are caused by changes in xyloglucan-degrading activity. Modifications of xyloglucan metabolism as well as the thickness of cell walls by gravity stimulus may be the primary event determining the cell wall extensibility, thereby regulating the growth rate of Arabidopsis hypocotyls.