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At least 163 records · Page 9Linked to original sources
PubMed2002

Arabidopsis OST1 protein kinase mediates the regulation of stomatal aperture by abscisic acid and acts upstream of reactive oxygen species production.

During drought, the plant hormone abscisic acid (ABA) triggers stomatal closure, thus reducing water loss. Using infrared thermography, we isolated two allelic Arabidopsis mutants (ost1-1 and ost1-2) impaired in the ability to limit their transpiration upon drought. These recessive ost1 mutations disrupted ABA induction of stomatal closure as well as ABA inhibition of light-induced stomatal opening. By contrast, the ost1 mutations did not affect stomatal regulation by light or CO(2), suggesting that OST1 is involved specifically in ABA signaling. The OST1 gene was isolated by positional cloning and was found to be expressed in stomatal guard cells and vascular tissue. In-gel assays indicated that OST1 is an ABA-activated protein kinase related to the Vicia faba ABA-activated protein kinase (AAPK). Reactive oxygen species (ROS) were shown recently to be an essential intermediate in guard cell ABA signaling. ABA-induced ROS production was disrupted in ost1 guard cells, whereas applied H(2)O(2) or calcium elicited the same degree of stomatal closure in ost1 as in the wild type. These results suggest that OST1 acts in the interval between ABA perception and ROS production. The relative positions of ost1 and the other ABA-insensitive mutations in the ABA signaling network (abi1-1, abi2-1, and gca2) are discussed.

Abscisic Acid↗
PubMed1994

Calcium-Activated K+ Channels and Calcium-Induced Calcium Release by Slow Vacuolar Ion Channels in Guard Cell Vacuoles Implicated in the Control of Stomatal Closure.

Stomatal closing requires the efflux of K+ from the large vacuolar organelle into the cytosol and across the plasma membrane of guard cells. More than 90% of the K+ released from guard cells during stomatal closure originates from the guard cell vacuole. However, the corresponding molecular mechanisms for the release of K+ from guard cell vacuoles have remained unknown. Rises in the cytoplasmic Ca2+ concentration have been shown to trigger ion efflux from guard cells, resulting in stomatal closure. Here, we report a novel type of largely voltage-independent K+-selective ion channel in the vacuolar membrane of guard cells that is activated by physiological increases in the cytoplasmic Ca2+ concentration. These vacuolar K+ (VK) channels had a single channel conductance of 70 pS with 100 mM KCI on both sides of the membrane and were highly selective for K+ over NH4+ and Rb+. Na+, Li+, and Cs+ were not measurably permeant. The Ca2+, voltage, and pH dependences, high selectivity for K+, and high density of VK channels in the vacuolar membrane of guard cells suggest a central role for these K+ channels in the initiation and control of K+ release from the vacuole to the cytoplasm required for stomatal closure. The activation of K+-selective VK channels can shift the vacuolar membrane to more positive potentials on the cytoplasmic side, sufficient to activate previously described slow vacuolar cation channels (SV-type). Analysis of the ionic selectivity of SV channels demonstrated a Ca2+ over K+ selectivity (permeability ratio for Ca2+ to K+ of ~3:1) of these channels in broad bean guard cells and red beet vacuoles, suggesting that SV channels play an important role in Ca2+-induced Ca2+ release from the vacuole during stomatal closure. A model is presented suggesting that the interaction of VK and SV channel activities is crucial in regulating vacuolar K+ and Ca2+ release during stomatal closure. Furthermore, the possibility that the ubiquitous SV channels may represent a general mechanism for Ca2+-induced Ca2+ release from higher plant vacuoles is discussed.

Journal Article↗
PubMed1995

The too many mouths and four lips mutations affect stomatal production in Arabidopsis.

Stomata regulate gas exchange through the aerial plant epidermis by controlling the width of a pore bordered by two guard cells. Little is known about the genes that regulate stomatal development. We screened cotyledons from ethyl methanesulfonate-mutagenized seeds of Arabidopsis by light microscopy to identify mutants with altered stomatal morphology. Two mutants, designated too many mouths (tmm) and four lips (flp), were isolated with extra adjacent stomata. The tmm mutation results in stomatal clustering and increased precursor cell formation in cotyledons and a virtual absence of stomata in the inflorescence stem. The flp mutation results in many paired stomata and a small percentage of unpaired guard cells in cotyledons. The double mutant (tmm flp) exhibits aspects of both parental phenotypes. Both mutations appear to affect stomatal production more than patterning or differentiation. tmm regulates stomatal production by controlling the formation, and probably the activity, of the stomatal precursor cell.

Arabidopsis↗
PubMed2006

ABA-induced NO generation and stomatal closure in Arabidopsis are dependent on H2O2 synthesis.

Nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) are key signalling molecules produced in response to various stimuli and involved in a diverse range of plant signal transduction processes. Nitric oxide and H(2)O(2) have been identified as essential components of the complex signalling network inducing stomatal closure in response to the phytohormone abscisic acid (ABA). A close inter-relationship exists between ABA and the spatial and temporal production and action of both NO and H(2)O(2) in guard cells. This study shows that, in Arabidopsis thaliana guard cells, ABA-mediated NO generation is in fact dependent on ABA-induced H(2)O(2) production. Stomatal closure induced by H(2)O(2) is inhibited by the removal of NO with NO scavenger, and both ABA and H(2)O(2) stimulate guard cell NO synthesis. Conversely, NO-induced stomatal closure does not require H(2)O(2) synthesis nor does NO treatment induce H(2)O(2) production in guard cells. Tungstate inhibition of the NO-generating enzyme nitrate reductase (NR) attenuates NO production in response to nitrite in vitro and in response to H(2)O(2) and ABA in vivo. Genetic data demonstrate that NR is the major source of NO in guard cells in response to ABA-mediated H(2)O(2) synthesis. In the NR double mutant nia1, nia2 both ABA and H(2)O(2) fail to induce NO production or stomatal closure, but in the nitric oxide synthase deficient Atnos1 mutant, responses to H(2)O(2) are not impaired. Importantly, we show that in the NADPH oxidase deficient double mutant atrbohD/F, NO synthesis and stomatal closure to ABA are severely reduced, indicating that endogenous H(2)O(2) production induced by ABA is required for NO synthesis. In summary, our physiological and genetic data demonstrate a strong inter-relationship between ABA, endogenous H(2)O(2) and NO-induced stomatal closure.

Abscisic Acid↗
PubMed2006

CDPKs CPK6 and CPK3 function in ABA regulation of guard cell S-type anion- and Ca(2+)-permeable channels and stomatal closure.

Abscisic acid (ABA) signal transduction has been proposed to utilize cytosolic Ca(2+) in guard cell ion channel regulation. However, genetic mutants in Ca(2+) sensors that impair guard cell or plant ion channel signaling responses have not been identified, and whether Ca(2+)-independent ABA signaling mechanisms suffice for a full response remains unclear. Calcium-dependent protein kinases (CDPKs) have been proposed to contribute to central signal transduction responses in plants. However, no Arabidopsis CDPK gene disruption mutant phenotype has been reported to date, likely due to overlapping redundancies in CDPKs. Two Arabidopsis guard cell-expressed CDPK genes, CPK3 and CPK6, showed gene disruption phenotypes. ABA and Ca(2+) activation of slow-type anion channels and, interestingly, ABA activation of plasma membrane Ca(2+)-permeable channels were impaired in independent alleles of single and double cpk3cpk6 mutant guard cells. Furthermore, ABA- and Ca(2+)-induced stomatal closing were partially impaired in these cpk3cpk6 mutant alleles. However, rapid-type anion channel current activity was not affected, consistent with the partial stomatal closing response in double mutants via a proposed branched signaling network. Imposed Ca(2+) oscillation experiments revealed that Ca(2+)-reactive stomatal closure was reduced in CDPK double mutant plants. However, long-lasting Ca(2+)-programmed stomatal closure was not impaired, providing genetic evidence for a functional separation of these two modes of Ca(2+)-induced stomatal closing. Our findings show important functions of the CPK6 and CPK3 CDPKs in guard cell ion channel regulation and provide genetic evidence for calcium sensors that transduce stomatal ABA signaling.

Abscisic Acid↗
PubMed1999

Ultrastructure of stomatal development in Arabidopsis (Brassicaceae) leaves.

Stomatal development was studied in wild-type Arabidopsis leaves using light and electron microscopy. Development involves three successive types of stomatal precursor cells: meristemoid mother cells, meristemoids, and guard mother cells (GMCs). The first two types divide asymmetrically, whereas GMCs divide symmetrically. Analysis of cell wall patterns indicates that meristemoids can divide asymmetrically a variable number of times. Before meristemoid division, the nucleus and a preprophase band of microtubules become located on one side of the cell, and the vacuole on the other. Meristemoids are often triangular in shape and have evenly thickened walls. GMCs can be detected by their roughly oval shape, increased starch accumulation, and wall thickenings on opposite ends of the cells. Because these features are also found in developing stomata, stomatal differentiation begins in GMCs. The wall thickenings mark the division site in the GMC since they overlie a preprophase band of microtubules and occur where the cell plate fuses with the parent cell wall. Stomatal differentiation in Arabidopsis resembles that of other genera with kidney-shaped guard cells. This identification of stages in stomatal development in wild-type Arabidopsis provides a foundation for the analysis of relevant genes and of mutants defective in stomatal patterning, cell specification, and differentiation.

Journal Article↗
PubMed2004

[Stomatal and nonstomatal limitations of photosynthesis in mung bean leaves under the combination of enhanced UV-B radiation and NaCl stress].

Stomatal and nonstomatal limitations of photosynthesis in mung bean (Phaseolus radiatus L.) leaves under the combination of 0.35 W/m(2) UV-B radiation and 0.4% NaCl stress were studied. Separated or combined treatments of enhanced UV-B radiation and NaCl stress all resulted in a decrease in net photosynthetic rate, stomatal conductance, photosynthetic ability, efficiency of CO(2) carboxylation and Rubisco content, and the extent of those decreases enhanced obviously with the increase of treatment days. Intercellular CO(2)concentration tended to decrease in short period, followed by a gradual increase and to be higher than the control on the seventh day after treatment under NaCl stress alone, while a tendency of gradual increase was observed under enhanced UV-B radiation alone or two stresses combined and the concentration was higher than the control after three day of treatments. By contrast, the tendency of stomatal limitation value was just reverse to the intercellular CO(2) concentration, but the stomatal limitation value was always higher than control under all stress conditions (did not include that on the fifth day under the combined stresses). As compared with an individual stress the effect of combined stress on the above parameters was more serious. These results indicate that under all stress conditions the inhibition of photosynthesis in mung bean leaves is the results of both stomatal and nonstomatal limitations. And the stomatal limitation is dominant in short period, nonstomatal limitation becomes the dominant one in longer period. The decrease in Rubisco content leads to nonstomatal limitation of photosynthesis under all stresses.

Phaseolus↗
PubMed2005

[NO may function in the downstream of H2O2 in ABA-induced stomatal closure in Vicia faba L].

It is usually suggested that either H(2)O(2) or NO function as a signal molecule in mediating the ABA-induced stomatal closure of guard cells, but there has been no report on the relationship between H(2)O(2) and NO in ABA signal transduction pathway. Here, using stomatal analysis and laser scanning cofocal microscope techniques, we show firstly that NO functions as a downstream intermediate of H(2)O(2) signaling to mediate ABA-induced stomatal closure in Vicia faba L. Sodium nitroprusside (SNP, a NO donor) and H(2)O(2) can mimic the effects of ABA on stomatal closure. Carboxy-PTIO (c-PTIO, a specific scavenger of NO) partly reverse the stomatal closure induced by ABA or H(2)O(2), while catalase (CAT), a H(2)O(2) scavenger, failed to reverse the NO-induced aperture reduction in Vicia faba guard cells. Monitoring the changes in both NO and H(2)O(2) generation in guard cells by using fluorescent probe of NO or H(2)O(2), DAF-2DA or H2DCFDA, respectively, we found that the generating rate of H(2)O(2) in guard cells was faster than that of NO after being treated with ABA 10 micromol/L. CAT almost completely inhibited the increase in DAF fluorescence induced by ABA. Similar to ABA, exogenous H(2)O(2) provoked the production of NO. c-PTIO slightly enhanced the fluorescent intensity of DCF stimulated by ABA, while exogenous SNP did not increase DCF fluorescence in guard cells. Taken together, these results suggest that H(2)O(2) could probably act as upstream component of NO signaling and NO negatively regulate H(2)O(2) generation during ABA-induced stomatal closure in guard cells.

Abscisic Acid↗
PubMed1980

Bovine papular stomatitis incidence in veterinary students.

Five cases of probable bovine papular stomatitis in faculty and students in a university veterinary clinic precipitated an intensive surveillance program. A senior class of veterinary medical students was questioned at the beginning of their clinical training to determine their history of exposure to cattle and presence of lesions resembling bovine papular stomatitis. Fifty-nine of the 115 students reported having had their hands in the mouths of cattle frequently. One of the 59 had experienced a hand lesion resembling bovine papular stomatitis. This class was maintained under close surveillance for bovine papular stomatitis-like lesions during the final 12 months of their clinical experience in veterinary school. One case developed in 8483 person days spent in the three high risk areas of beef cattle service, dairy cattle service and large animal anesthesiology. These two bovine papular stomatitis cases compare in frequency with five class members who had been vaccinated as a result of exposure to rabid animals and two class members with brucella antibodies in their sera. The findings suggest bovine papular stomatitis infections are not unusual in veterinary students but the mild clinical manifestations make the condition relatively unimportant.

Animals↗
PubMed2000

Vesicular stomatitis and other vesicular, erosive, and ulcerative diseases of horses.

Physical trauma, dietary factors, certain toxins, immune mediated disorders, and vesicular stomatitis virus (VSV) infection are known causes of stomatitis in horses. There is evidence that some outbreaks of equine stomatitis are caused by as yet unidentified infectious agents. It remains to be determined whether stomatitis is an emerging equine infectious disease, or if the increase in reported cases is simply the result of greater public awareness as a consequence of widespread outbreaks of VSV in the southwestern United States in recent years. Focused laboratory and epidemiological studies are necessary to more adequately define non-VS related infectious and noninfectious causes of equine stomatitis.

Animals↗
PubMed1999

Vesicular stomatitis.

Vesicular stomatitis is a disease of livestock caused by some members of the Vesiculovirus genus (Family Rhabdoviridae), two of which are called 'vesicular stomatitis virus'. Clinical disease presents as severe vesiculation and/or ulceration of the tongue, oral tissues, feet, and teats, and results in substantial loss of productivity. Except for its appearance in horses, it is clinically indistinguishable from foot-and-mouth disease. Unlike foot-and-mouth disease, it is very infectious for man and can cause a temporarily debilitating disease. Vesicular stomatitis occurs seasonally every year in the southeastern USA, southern Mexico, throughout Central America and in northern South America, and emerges from tropical areas to cause sporadic epidemics in cooler climates during the summer months. Other Vesiculoviruses are endemic in India and Africa. Vesiculoviruses are arthropod-borne and it is possible they are actually well adapted insect viruses that incidentally infect mammals. Vesiculoviruses are relatively simple, having a linear, single stranded, negative sense RNA genome encased in a bullet-shaped virion made from only five proteins. Upon infection of cultured cells, viral products turn off cellular gene expression and seize the entire metabolic potential of the cell. They also depolymerize the cytoskeleton to cause rapid tissue destruction. Virus infection in animals provokes interferon and nitric oxide responses, which quickly control viral replication, and an antibody response that prevents further viral replication. Vesiculovirus genome replication is error-prone, resulting in viral progeny containing many variants. This allows rapid adaptation. Nevertheless, vesicular stomatitis virus genomic sequences appear relatively stable within single endemic areas, and vary progressively on a North-South axis in the Western Hemisphere. Numerous important fundamental discoveries in immunology and virology have come from recent studies of vesicular stomatitis virus. However, these discoveries have not led to a safe and fully effective vaccine for man or beast. In the absence of a vaccine, the continual increase in rapid intercontinental travel, the increase in numbers and concentration of susceptible animals, the plasticity of the viral genome, and the underappreciation of vesiculoviruses as veterinary and zoonotic pathogens by regulators and biomedical researchers, are combining with potentially explosive consequences.

Animals↗
PubMed1987

Denture stomatitis: a review.

Denture stomatitis has been reported in 11-67% of complete denture wearers. It is more common on the palatal mucosa and in female patients. In Newton's type I denture stomatitis, where the inflammation remains focal, trauma seems to be responsible. In Newton's types II and III denture stomatitis, where the denture-bearing mucosa is diffusely involved, most workers assert that the aetiology is multi-factorial. Evidence is presented incriminating Candida albicans colonization of the fitting surface of the prosthesis in many cases of denture stomatitis promoted by continuous denture wearing. Allergic and primary irritant reactions to the denture base material, systemic predisposing factors including dietary deficiency and haematological disorders, also play a part. In most cases of denture stomatitis, elimination of denture faults, control of denture plaque and discontinuous denture wearing are sufficient treatment. The routine use of antiseptic or antimycotic drugs seems unnecessary.

Denture, Complete↗
PubMed1987

Clinico-pathological study on denture stomatitis.

The clinical and pathological study was performed in order to determine the histopathological and cytoimmunological characteristics of denture stomatitis. All specimens were biopsy materials from seventeen patients with denture stomatitis. Normal palatal mucosae from ten patients served as the control. In addition to the usual staining methods, naphtol AS-D chloroacetate esterase stain and peroxidase-antiperoxidase method were used to detect mast cells and plasma cells. Denture stomatitis could be divided into atrophic and hyperplastic types. The former showed a smooth and atrophic mucosa. The latter showed a large number of exophytic projections which were composed of marked acanthosis and submucosal fibrosis, and was further subdivided into granular and papillary subtype according to the size of projections. In the present study, there were six cases of the atrophic type, and eleven cases of the hyperplastic type (consisting of seven granular and four papillary subtypes). The hyperplastic type was more frequently observed in patients with partial dentures compared with complete dentures and was associated frequently with ill fitting of the denture base as well as agglutination of denture plaque. Cytoimmunological study revealed that there was a pronounced increase of plasma cells, especially IgG- and IgA-producing cells, and a moderate increase of lymphocytes as well as mast cells in both types of denture stomatitis. Mast cells were always noted in the area with marked plasma cell infiltration, suggesting an intimate relation between both cells. These findings suggest that the immunological reactions play some role in the pathogenesis of denture stomatitis.

Adolescent↗
PubMed1983

Quantitative relationship between yeast and bacteria in denture-induced stomatitis.

Quantitative cultural studies of yeasts and bacteria were made from 7-day-old denture plaque accumulate on pieces of self-adhesive tape stuck on the fitting surface of the maxillary denture in 17 edentulous subjects with healthy oral mucosa and in 27 patients affected with denture-induced stomatitis. Significantly higher numbers of yeasts and bacteria were cultured in the stomatitis patients than in the controls. This indicates that the rate of plaque formation is increased in patients with denture-induced stomatitis. Yeasts usually constituted less than 1% of the anaerobic bacterial counts, but the percentage of yeasts was significantly higher in the stomatitis patients than in the controls. There was a significant correlation between initially higher yeast counts and improvement of the clinical condition of the palatal mucosa following antimycotic treatment. In some patients only bacteria were grown and antimycotic treatment had no effect. The study supported the contention that yeast antigens and toxins of denture plaque are significant factors in initiation and maintenance of denture-induced stomatitis. However, bacteria may also be involved as pathogens.

Aged↗
PubMed2004

Effect of strain and serotype of vesicular stomatitis virus on viral shedding, vesicular lesion development, and contact transmission in pigs.

OBJECTIVE: To determine whether pigs can be infected with strains of vesicular stomatitis virus New Jersey (VSV-NJ) and vesicular stomatitis virus Indiana (VSV-I) isolated during recent vesicular stomatitis outbreaks that primarily involved horses in the western United States and determine the potential for these viruses to be transmitted by contact. ANIMALS: 128 pigs. PROCEDURE: Pigs were challenged with VSV-NJ or VSV-I from the 1995 and 1997 outbreaks of vesicular stomatitis in the western United States, respectively, or with VSV-NJ (OS) associated with vesicular stomatitis in feral pigs on Ossabaw Island, Ga. Pigs (3/group) were inoculated with each virus via 3 routes and evaluated for viral shedding, seroconversion, and the development of vesicular lesions. In another experiment, the potential for contact transmission of each virus from experimentally infected to naïve pigs was evaluated. RESULTS: Infection of pigs was achieved for all 3 viruses as determined by virus isolation and detection of seroconversion. In inoculated pigs, all 3 viruses were isolated from multiple swab samples at concentrations sufficient to infect other pigs. However, compared with results obtained with the 2 VSV-NJ strains, viral titers associated with VSV-I were low and the duration of virus shedding was reduced. Results from the contact transmission trials were consistent with these results; virus transmission was detected most frequently with the VSV-NJ strains. CONCLUSIONS AND CLINICAL RELEVANCE: Pigs can be infected with VSV-NJ and VSV-I. Differences in the extent of viral shedding and potential for contact transmission were apparent between serotypes but not between the VSV-NJ strains investigated.

Animals↗
PubMed1975

Denture stomatitis. A clinical, electron-microscopic, microradiographic and light-microscopic study.

The present study includes a reexamination of 10 patients who, two years ago received complete upper and lower denture treatment to eliminate an existing denture stomatitis. Clinical healing of the denture stomatitis was obtained only in one patient, whereas the remaining nine patients wtill displayed an obvious denture stomatitis. Biopsies were taken from the palatal mucosa and examined histologically, microradiographically, and by electron microscopy. The results of these examination indicated that, in denture stomatitis there is a reduced thickness of the epithelium, an absence of a stratum corneum, a markedly widened intercellular space, especially in the stratum basale, and an intense infiltration of inflammatory cells, plasma cells and lymphocytes in the connective tissue, as well as in the epithelium. These changes are characteristic features of an inflammatory process, and similar to the changes which occur, for example, in chronic, marginal gingivitis. The composition of the inflammatory infiltrate suggested that, in denture stomatitis, immunological phenomena influence the pattern of the tissue reaction.

Alveolar Process↗
PubMed1984

Development of an immunoelectroosmophoresis test for the detection and typing of antibodies to vesicular stomatitis viruses.

This study was conducted to develop a rapid test to detect type specific antibodies to various strains of vesicular stomatitis virus. Glycoprotein was extracted from purified vesicular stomatitis virus-Indiana 3 and used as antigen in an immunoelectroosmophoresis test (counter immunoelectrophoresis) to test reactivity with homologous hyperimmune serum and antisera to vesicular stomatitis virus-New Jersey, Indiana 1 and Indiana 2. A reaction was only detected with the homologous antiserum. A simpler preparation of antigen, a detergent extract of infected cells was also evaluated and shown to have less specificity in reactions with hyperimmune sera. This infected cell extract was, however, useful in detecting homologous antibodies in convalescent sera (natural vesicular stomatitis virus-New Jersey infection) and no reactions were detected with infected cell extracts of vesicular stomatitis virus-Indiana 1, 2 and 3.

Animals↗
PubMed1981

Whole saliva albumin as an indicator of stomatitis in cancer therapy patients.

Albumin concentrations were measured in whole and parotid saliva samples collected from patients who were undergoing various cancer treatment protocols and had a high incidence of stomatitis. Oral examinations were made at the time of saliva collection and the degree of stomatitis evaluated. Elevations of whole saliva albumin concentrations were observed in 11 stomatitis incidents. No increases were observed in parotid saliva. The salivary albumin increases always preceded and often occurred in the absence of stomatitis, suggesting that the whole saliva albumin level may be a useful measure and predictor of this condition. If so, monitoring of this parameter could be useful in establishing treatment schedules for chemotherapy protocols that have stomatitis as the limiting factor in treatment.

Adolescent↗