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PubMed2003

Enzyme immunoassays for the investigation of protein nitration by air pollutants.

Two enzyme immunoassays have been developed, characterised, and applied to investigate protein nitration in birch pollen extract (BPE) and bovine serum albumin (BSA) samples exposed to air pollutants. The monoclonal antibody CAY-189542 against nitrotyrosine (raised against peroxynitrite-treated keyhole limpet hemocyanine) was characterised in an indirect competitive assay (affinity and cross-reactivities) and applied in a new one-sided enzyme immunoassay for nitrated proteins. The one-sided assay was calibrated against a nitrated BSA standard with an average of 14 nitrotyrosine residues per molecule (nitro-(14)-BSA; detection limit 8.3 pmol L(-1)), and the sensitivity of the test was found to be significantly enhanced by a multivalent binding mode of the monoclonal antibody (bonus effect of multivalency). The same antibody and a polyclonal antibody against Bet v 1, the most prominent birch pollen allergen, were used in a new sandwich immunoassay for specific determination of nitrated Bet v 1. This assay was calibrated against a nitrated Bet v 1 standard with an average of 3 nitrotyrosine residues per molecule (nitro-(3)-Bet v 1; detection limit 0.2 nmol L(-1)). Bet v 1 and BSA exposed to polluted urban outdoor air and to synthetic gas mixtures containing NO2 and O3 at atmospherically relevant concentration levels were found to be efficiently nitrated within hours to days. Pronounced correlations of nitro-(14)-BSA equivalent concentrations with exposure time and with nitro-(3)-Bet v 1 equivalent concentrations in nitrated BPE samples were observed. Test experiments indicated that the efficiency of protein nitration was strongly enhanced by reactive species formed upon interaction of NO2 with O3 and H2O (e.g. NO3 and HNO3). Potential implications of protein nitration by air pollutants are outlined and discussed.

Air Pollutants↗

PubMed1998

Why is allergy increasing?--environmental factors.

Data from epidemiological studies have shown that allergic conditions have increased over the last 30-40 years, particularly in developed countries, despite a decrease in the severity of grass pollen seasons. Other epidemiological studies suggest an interaction between allergic diseases and traffic pollution, and laboratory findings indicate that diesel exhaust particles enhance sensitivity to allergens. In an in vitro study, we found evidence to suggest that cigarette smoke may render the airway epithelium more susceptible to adverse effects of allergens. Evidence from other studies indicates that O3 and NO2, with or without SO2, can enhance the airway allergic response in susceptible individuals such as those with asthma and rhinitis. Studies investigating cellular and subcellular mechanisms suggest that pollutants are likely to influence the actions and interactions of a variety of cells, and lead to the synthesis of proinflammatory mediators that modulate the activity and functions of inflammatory cells.

Allergens↗

PubMed1998

Specific antigen targeting to surface IgE and IgG on mouse bone marrow-derived mast cells enhances efficiency of antigen presentation.

The discovery that bone marrow-derived mast cells can express major histocompatibility complex class II molecules and act as antigen-presenting cells prompted us to evaluate this function when antigen is internalized through fluid-phase endocytosis or via specific uptake by using IgG and IgE antibodies. This study was performed using a specific T-cell hybridoma developed against Lol p 1, the major allergen of grass pollen Lolium perenne. Expression of Fc gamma R and Fc epsilon RI by mast cells led us to investigate the influence of IgG- and IgE-targeted antigen on the antigen-presenting function of mast cells. Internalization of Lol p 1 through different specific IgG monoclonal antibodies (mAb) resulted in the activation of Lol p 1-specific T-cell hybridoma at concentrations about 100-fold less than that required for T-cell stimulation by uncomplexed antigen. IgE-complexed Lol p 1, which facilitates trapping of antigen by mast cells, induced an accelerated and more efficient antigen-presenting capacity of mast cells than that obtained with uncomplexed antigen. However, aggregation of anti-dinitrophenyl (DNP) IgE mAb by the irrelevant antigen DNP-human serum albumin did not substantially increase the capacity of mast cells to present Lol p 1 to T cells. This suggests that the mere aggregation of Fc epsilon RI is not sufficient for enhanced antigen presentation mediated by IgE. Tissue distribution and strategic location of mast cells at the mucosal barriers and their capacity to process the antigen through efficient fluid-phase pinocytosis as well as IgG- and IgE-dependent targeting of antigens provide mast cells with a prominent role in immune surveillance.

Allergens↗

PubMed2000

The importance of allergens in the development of asthma and the persistence of symptoms.

The importance of allergies and allergens in the development and persistence of asthma is suggested by 3 lines of evidence. First, a number of epidemiologic studies demonstrate that sensitization to indoor allergens and the spores of the outdoor seasonal fungus Alternaria is a risk factor for the development of asthma in both children and adults. Sensitivity to pollens, on the other hand, rarely constitutes a risk for asthma but does constitute a risk for seasonal allergic rhinitis. Second, several studies, again in both children and adults, have demonstrated that, in persons sensitive to indoor allergens, the severity of asthma symptoms will vary with the level of exposure. Third, the elimination of exposure to house-dust mites has produced a remarkable reversal of asthma in sensitive children and adults. Not only have symptoms and pulmonary function improved, but there has also been evidence of a reduction in airway inflammation and hyperresponsiveness. Taken together, these studies make a strong argument for the importance of allergy and allergen exposure as aggravating factors in asthma in both children and adults and reinforce the importance of the identification and treatment of these allergen sensitivities.

Adult↗

PubMed2001

The importance of allergens in the development of asthma and the persistence of symptoms.

Adult↗

PubMed2002

Integration of alien plants into a native flower-pollinator visitation web.

Introduced alien species influence many ecosystem services, including pollination of plants by animals. We extend the scope of recent 'single species' studies by analysing how alien plant species integrate themselves into a native flower visitation web. Historical records for a community in central USA show that 456 plant species received visits from 1429 insect and 1 hummingbird species, yielding 15 265 unique interactions. Aliens comprised 12.3% of all plant species, whereas only a few insects were alien. On average, the flowers of alien plants were visited by significantly fewer animal species than those of native plants. Most of these visitors were generalists, visiting many other plant species. The web of interactions between flowers and visitors was less richly connected for alien plants than for natives; nonetheless, aliens were well integrated into the native web. Because most visitors appear to be pollinators, this integration implies possible competitive and facilitative interactions between native and alien plants, mediated through animal visitors to flowers.

Animals↗

PubMed2000

Insights into a key developmental switch and its importance for efficient plant breeding.

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Abscisic Acid↗

PubMed2001

Climate change as the dominant control on glacial-interglacial variations in C3 and C4 plant abundance.

Although C4 plant expansions have been recognized in the late Miocene, identification of the underlying causes is complicated by the uncertainties associated with estimates of ancient precipitation, temperature, and partial pressure of atmospheric carbon dioxide (PCO2). Here we report the carbon isotopic compositions of leaf wax n-alkanes in lake sediment cores from two sites in Mesoamerica that have experienced contrasting moisture variations since the last glacial maximum. Opposite isotopic trends obtained from these two sites indicate that regional climate exerts a strong control on the relative abundance of C3 and C4 plants and that in the absence of favorable moisture and temperature conditions, low PCO2 alone is insufficient to drive an expansion of C4 plants.

Alkanes↗

PubMed1994

Effect of the 5-lipoxygenase inhibitor ZD2138 on allergen-induced early and late asthmatic responses.

BACKGROUND: Leukotrienes are lipid mediators generated from arachidonic acid by the 5-lipoxygenase pathway which may play an important part in the pathophysiology of asthma. Previous studies have demonstrated attenuation of the allergen-induced early and late asthmatic responses by leukotriene receptor antagonists. The effect of the 5-lipoxygenase inhibitor ZD2138, a non-redox lipoxygenase inhibitor which inhibits leukotriene synthesis for 24 hours after single doses of 350 mg, on allergen-induced early and late asthmatic responses has been assessed. METHODS: Eight asthmatic subjects with baseline FEV1 > 70% were studied. On screening, all subjects developed an allergen-induced biphasic asthmatic response to grass pollen, cat dander, or house dust mite. ZD2138 (350 mg) or placebo was given on two occasions separated by two weeks in a randomised double blind fashion. Allergen inhalation challenge was performed four hours after dosing and FEV1 was measured for eight hours. The inhibitory activity of ZD2138 on the 5-lipoxygenase pathway was assessed by measurements of calcium ionophore-stimulated generation of LTB4 in whole blood ex vivo and by analysis of urinary LTE4 levels before administration of drug or placebo and at regular intervals after oral drug dosing and allergen challenge. RESULTS: ZD2138 produced no significant bronchodilatation or attenuation of the early or late asthmatic response, although there was 82% inhibition of whole blood generation of LTB4 in response to calcium ionophore stimulation and 52% reduction in urinary excretion of LTE4. CONCLUSIONS: In asthmatic subjects the 5-lipoxygenase inhibitor ZD2138 did not protect against allergen-induced asthmatic responses, despite substantial inhibition of 5-lipoxygenase.

Adult↗

PubMed1988

Microbial infection or trauma at cardiovascular representation area of medulla oblongata as some of the possible causes of hypertension or hypotension.

The author found that the onset of hypertension or hypotension is relatively often associated with infections or development of so-called "sneezing due to allergy to pollen or dust," with or without headache, or due to trauma to the occipital area of the head. Using the "Bi-Digital O-ring Test," it was possible to demonstrate that, among bacterial and viral infections, the most common cause of infection associated with the appearance of hypertension is chlamydia, herpes simplex virus, cytomegalovirus, or Epstein-Barr virus. Particularly chlamydia and/or herpes simplex virus, with or without coexistence of other microbes, is usually present at the heart representation area of the medulla oblongata, especially at the left ventricular representation area, often accompanied by upper respiratory infection, cephalic, cervical or facial pain, with or without coexisting genito-urinary infection. The left ventricular representation area of the medulla oblongata is usually located at the right side. In most hypertensive patients, the left ventricular representation area of the medulla oblongata is enlarged up to 3 or 4 times normal size. Sufficient antibiotic treatment of chlamydia with erythromycin sometimes eliminated severe hypertension which appeared after chlamydia infection. In the presence of viral infections, such as herpes simplex, which is also causing severe pain in the head or neck, oral administration of acyclovir, erythromycin, or EPA (Eicosa Pentaenoic acid)-DHA (docosa hexaenoic acid) Omega 3 fish oil often reduced associated intractable pain and hypertension toward the normal level. Thus, the author is proposing new possible mechanisms as among the causes of so-called essential hypertension as a result of microbial infection or trauma of the cardiovascular representation area, particularly that of the left ventricular representation area at the right side of the medulla oblongata.

Acupuncture Therapy↗

PubMed2003

[Pollination and pollinators in the vegetation of the coastal plain of Paraguaná, Falcón State, Venezuela].

Pollination systems and plant-pollinator dynamics were studied for 51 plant species according to life form, vegetation type, and flowering phenology in the Paraguaná peninsula, Venezuela. A total of 43 species of floral visitors were recorded from which only 33 (76.7%) were effective pollinators and ten only visitors. Pollinator fauna consisted only of insects. Six pollinating agent classes were identified in the area of study. Pollinating bees were the most important class (35.1%), followed by butterflies (24.3%) and flies (13.5%). This trend was similar for the psamophilous and mangrove vegetation, but pollinating wasps were the third in importance in the littoral vegetation. Temporal distribution of pollinating agent classes showed a peak during the flowering peak, and during the lowest level of rainfall in the locality. Pollination systems were mostly polyphilous (62.7%) followed by monophilous (27.4%), and oligophilous species (7.8%). This trend was found to be similar for the different vegetation types and life forms. In a similar way, pollinator agents were mainly polytropic (60.4%), followed by monotropic (24.6%) and oligotropic species (14.8%). Plant species/pollinator species ratio was close to one for all vegetation types in the Paraguaná peninsula. Besides, the average number of pollinator species per plant species was 2.2, and the average number of plant species pollinated per insect species was 2.7. Plant species/pollinator species ratio and the average values of pollinator and plant species indicate a diffuse and symmetric relation between pollinator and plant species. These results are discussed in the context of the dynamics of pollination.

Animals↗

PubMed1993

Molecular genetics of cell interactions in Arabidopsis.

Many events in plant development are regulated by the interactions of neighboring cells. We are interested in determining what sorts of molecules act as signals and/or receptors in these interactions and how these mechanisms relate to those used in animals and fungi. We are presently working on two different types of systems to try to address this question. In one case we are starting at the molecular level and characterizing a family of receptor protein kinase genes which seem natural candidates for mediating cellular interactions. By analyzing the expression patterns of these genes as well as the phenotypes of transgenic plants bearing altered genes we hope to determine what roles these proteins play in plant development. In the second case we are starting from the organismic level and using genetics to identify genes essential to a whole range of cellular interactions which are required for proper male gametophyte development during reproduction. These interactions involve both recognition of the pollen grain to verify that it is from the correct species and also a transfer of positional information from the female to the male which first allows the pollen tube to determine the polarity of the stigmatic cell on which it has germinated and later provides 'guidance' for the elongating tube to find the ovule.

Arabidopsis↗

PubMed1996

Modification of reproductive development in Arabidopsis thaliana under spaceflight conditions.

Reproductive development in Arabidopsis thaliana (L.) Heynh. cv. Columbia plants was investigated under spaceflight conditions on shuttle mission STS-51. Plants launched just prior to initiation of the reproductive phase developed flowers and siliques during the 10-d flight. Approximately 500 flowers were produced in total by the 12 plants in both the ground control and spaceflight material, and there was no significant difference in the number of flowers in each size class. The flower buds and siliques of the spaceflight plants were not morphologically different from the ground controls. Pollen viability tests immediately post-flight using fluorescein diacetate indicated that about 35% of the pollen was viable in the spaceflight material. Light-microscopy observations on this material showed that the female gametophytes also had developed normally to maturity. However, siliques from the spaceflight plants contained empty, shrunken ovules, and no evidence of pollen transfer to stigmatic papillae was found by light microscopy immediately post-flight or by scanning electron microscopy on fixed material. Short stamen length and indehiscent anthers were observed in the spaceflight material, and a film-like substance inside the anther that connected to the tapetum appeared to restrict the release of pollen from the anthers. These observations indicate that given appropriate growing conditions, early reproductive development in A. thaliana can occur normally under spaceflight conditions. On STS-51, reproductive development aborted due to obstacles in pollination or fertilization.

Arabidopsis↗

PubMed1991

Protein analysis during the ontogeny of normal and male sterile stamenless-2 mutant stamens of tomato (Lycopersicon esculentum Mill.).

The levels and synthesis of proteins during the ontogeny of normal and male sterile stamenless-2 (sl-2/sl-2) mutant stamens of tomato (Lycopersicon esculentum) were examined. The mutant stamens contained low levels of soluble protein which were related to reduction in protein synthesis. The mutant stamens, however, possessed many polypeptides similar to the normal and synthesized a 53-kd polypeptide at stages when there are abnormalities in tapetum development. The mutant stamens also possessed a 23-kd and some low molecular weight polypeptides that were considered as degradative proteins. Normal stamens exhibited the synthesis of many polypeptides not found in the mutant, from microspore mother cell to the preanthesis stages. In addition, at the time of pollen maturation there was a greater synthesis of several polypeptides, particularly those of 42 and 37 kd. Although the causative mechanisms of male sterility in the sl-2/sl-2 mutant are not known, the synthesis, and the lack, of specific polypeptides reported here appears to be associated with pollen degeneration.

Gene Expression↗

PubMed2005

Oscillatory ROP GTPase activation leads the oscillatory polarized growth of pollen tubes.

Oscillation regulates a wide variety of processes ranging from chemotaxis in Dictyostelium through segmentation in vertebrate development to circadian rhythms. Most studies on the molecular mechanisms underlying oscillation have focused on processes requiring a rhythmic change in gene expression, which usually exhibit a periodicity of >10 min. Mechanisms that control oscillation with shorter periods (<10 min), presumably independent of gene expression changes, are poorly understood. Oscillatory pollen tube tip growth provides an excellent model to investigate such mechanisms. It is well established that ROP1, a Rho-like GTPase from plants, plays an essential role in polarized tip growth in pollen tubes. In this article, we demonstrate that tip-localized ROP1 GTPase activity oscillates in the same frequency with growth oscillation, and leads growth both spatially and temporally. Tip growth requires the coordinate action of two ROP1 downstream pathways that promote the accumulation of tip-localized Ca2+ and actin microfilaments (F-actin), respectively. We show that the ROP1 activity oscillates in a similar phase with the apical F-actin but apparently ahead of tip-localized Ca2+. Furthermore, our observations support the hypothesis that the oscillation of tip-localized ROP activity and ROP-dependent tip growth in pollen tubes is modulated by the two temporally coordinated downstream pathways, an early F-actin assembly pathway and a delayed Ca2+ gradient-forming pathway. To our knowledge, our report is the first to demonstrate the oscillation of Rho GTPase signaling, which may be a common mechanism underlying the oscillation of actin-dependent processes such as polar growth, cell movement, and chemotaxis.

Actin Cytoskeleton↗

PubMed1992

Cell interactions in plants.

Plant cells interact during development through diverse mechanisms that range from genetically encoded signals to physical stresses. Pollen self-incompatibility is the best understood cell interaction in plants. Analysis of genes that appear to be involved in specific developmental signals, such as liguleless1 from maize and GLABROUS1 from Arabidopsis, will provide clues as to the nature of cell interactions in plant development. Recent data suggest that intercellular connections may be more similar in plants and animals than previously thought.

Cell Communication↗

PubMed2000

Pollination in the marine realm: microsatellites reveal high outcrossing rates and multiple paternity in eelgrass Zostera marina.

The mating system was examined in two annual populations of eelgrass (Zostera marina), a marine angiosperm displaying subaqueous pollination. Multilocus genotyping using microsatellite DNA markers allowed the assessment of the pollen source based on single progeny as units of observation. Outcrossing was detectable by the presence of non-maternal alleles at one or more of the loci. In outcrossing cases, three microsatellite alleles were present in unripe seeds, consisting of both maternal alleles and the paternal allele composing the triploid primary endosperm. In ripe seeds, only the diploid embryonal genotype was amplifiable by PCR. Two intertidal populations situated in the German Wadden Sea were almost entirely outcrossing (t +/- SE 0.96 +/- 0.03, N=60 and 0.97 +/- 0.029, N=37). Because of the high polymorphism displayed by the eight chosen microsatellites, representing a total of 69 and 76 alleles, the likelihood of erroneously inferring selfing was small (alpha=0.0026 and 0.0007). In order to study the correlation of paternity, the coefficient of relatedness was determined within sibships. Relatedness (r +/- SE) was calculated as 0.357 +/- 0.059 and 0.343 +/- 0.037, indicating multiple paternities within inflorescences. Small amounts of tissue (< or = 0.1 mg) such as the developing seeds of recently fertilized ovules, were sufficient for PCR-amplification. Hence, PCR-based methods, such as multilocus microsatellite genotyping, allow the detection of pollen origin early in the development of progeny. They will be useful to distinguish postfertilization processes such as selective abortion and germination from other prefertilization determinants of plant mating systems.

Crosses, Genetic↗

PubMed2005

Clinical trial design, nasal allergen challenge models, and considerations of relevance to pediatrics, nasal polyposis, and different classes of medication.

Clinical trials in allergic rhinitis present several specific difficulties. In seasonal pollen-related disease, there are variations between subjects in the extent of pollen sensitization, individual variations in exposure to pollen even within a set area because of lifestyle differences, and variations between different areas in pollen counts and weather patterns. Thus, large patient numbers are needed in multicenter trials to account for such variations when the standard endpoint is symptom reporting. Furthermore, a pollen season may be relatively short (eg, lasting 6-8 weeks), and the pollen count is inconsistent during this period. Crossover study designs are thus inappropriate, and trials are usually conducted with a parallel-group design. This further increases the trial sample size as it reduces statistical power. These large patient numbers must be recruited over a very short period. Perennial house dust mite-sensitive allergic rhinitis presents other problems. Although there is less disease variation, it is appreciated that symptoms may be induced by nonallergic as well as allergic mechanisms because of the nasal hyperresponsiveness. The nonallergic symptoms may not be modified by treatments based on allergic disease mechanisms. Thus, symptom outcomes--although relevant to the patient--may not adequately reflect the pharmacologic efficacy of the specific intervention. To control variability and focus on allergic disease mechanisms, nasal allergen challenge has been used in drug development. Single-dose challenges in the laboratory or in a pollen chamber, which allow many volunteers to be studied at the same time, have proven useful in the evaluation of drugs that afford acute symptom relief. However, such challenges incompletely model naturally occurring disease, in which the repeated daily exposure to allergen modifies the mucosal inflammatory cell profile and in particular promotes the epithelial accumulation of effector cells. This alters the response to allergen exposure. To model this, repeated low-dose daily allergen exposure has been used to generate these mucosal changes artificially, and early studies suggest that this may be a more valid model for the evaluation of anti-inflammatory therapy. However, little has been published with this model. Different disease groups are associated with their own specific issues in clinical trials. The pediatric population, in which allergic rhinitis is common, has different requirements for education, quality of life evaluation, and adverse-event monitoring; nasal polyposis, because of the nature of the disease, requires additional means of assessment, such as nasal endoscopy and imaging (eg, computerized tomography scanning), as well as attention to additional outcome measures (eg, the measurement of sense of smell). Within clinical trial design, there are important questions to be considered in relationship to the therapeutic intervention. Should this be given topically or systemically? What are the appropriate timing and frequency of medication? Does the disease itself modify the treatment efficacy, and does combination therapy afford better clinical outcome than single-modality therapy? These issues are discussed, and the influences of current therapies on objective outcome measures in allergic rhinitis are reviewed.

Adolescent↗