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PubMed2004

Nutritional suitability of corn pollen for the predator Coleomegilla maculata (Coleoptera: Coccinellidae).

The nutritional suitability of corn pollen for the facultatively phytophagous predator Coleomegilla maculata was studied in the laboratory. Dry matter, organic matter, ash, crude protein, amino acid, and quercetin contents of pollen from 10 hybrids of field corn were determined. C. maculata were reared on pollen or aphids + artificial diet for their entire lives; larval duration, post-mortem adult dry weights, fecundity within 7 days of mating, and mortality rates were compared among the treatments. In another experiment, C. maculata larvae were reared on pollen; weight gained, pollen ingested, and frass produced were compared among instars. Also, consumption relative to increases in larval biomass and the efficiency with which larvae converted corn pollen into biomass were compared among instars. Beetles reared on aphids had greater weights and fecundity and a shorter larval duration relative to the pollen-fed beetles. The percentages of organic matter and ash in corn pollen were significantly correlated with C. maculata mortality, and we hypothesize that some micronutrient or phytochemical is at sub-optimal levels for C. maculata development in some of the pollens. We observed an increase in the conversion efficiency of pollen and a decrease in the consumption relative to biomass of C. maculata as the larvae aged, which suggests a physiological or behavioral alteration in the feeding behavior of C. maculata during the larval stage.

Animal Feed↗
PubMed1994

Airway provocation test with ragweed pollen extract in Chinese asthmatics.

As ragweed becomes widespread over China, ragweed pollenosis tends to be more frequent. Incidence of ragweed pollenosis is about 1.04% in Qingdao district. To elucidate ragweed as an allergen in the development of bronchial asthma, ragweed pollen extract inhalation airway provocation tests (APT) were studied in 55 patients with ragweed pollenosis. A single dosage of 9,000 PNU ragweed pollen extract was applied and positive response was defined as more than 35% fall in SGrs at the dose of PT35-Grs. Among 55 patients, positive APTs were found in 27 cases (49%), dual late-phase responses in 11 patients, single late-phase responses in 2 patients in the complicated asthma group. Late-phase responses were related to the increased specific IgE and strong positive skin test response (wheal > 11 mm). The results suggested ragweed pollen was one of the important allergens causing bronchial asthma. There was airway hyperresponsiveness to ragweed pollen in some patients (20%) with ragweed pollenosis without asthmatic symptoms.

Adolescent↗
PubMed2000

Estimation of gene flow in the tropical-rainforest tree Neobalanocarpus heimii (Dipterocarpaceae), inferred from paternity analysis.

Pollen flow and population genetic structure among 30 potentially flowering individuals of Neobalanocarpus heimii, a tropical emergent tree, were investigated in a lowland tropical rainforest of Malaysia using microsatellite polymorphism. The 248 offspring in the vicinity of five reproductive trees of the 30 potentially flowering trees were used in paternity analysis for pollen-flow study. Four primer pairs, developed in different species of dipterocarps, were adopted to detect microsatellite polymorphism. Based upon microsatellite polymorphism, pollen flow and seed migration were detected. Pollen-flow events of more than 400 m were observed directly, based on paternity analysis in the study plot. The estimated average mating distance of the five reproductive trees was 524 m. This result suggests that reproduction of this species is mediated by a long-distance pollinator. The haplotypes of some offspring were not compatible with the nearest reproductive tree. Thus, the results suggest that some seeds are dispersed by a seed dispersal vector. Investigation of genetic structure showed significant and negative correlation of genetic relatedness and spatial distances between the 30 potentially flowering trees, but this correlation was weak. We suggest that long-distance gene flow and seed migration are responsible for the poorly developed genetic structure of this species.

Ecosystem↗
PubMed1989

Biological and cellular responses to grass pollen in sensitive patients.

Using a noninvasive skin chamber technique, we studied the in vivo development of anaphylactic reactions in 8 pollen-sensitive patients suffering from seasonal allergic rhinitis/conjunctivitis/asthma and showing positive cutaneous reactions after intradermal allergen challenge. As agonists, histamine and pollen were introduced into the skin chambers and left in contact with superficial dermis during 6 h. The release of mediators (histamine and prostaglandin [PG] D2) and the modifications in protein diffusion occurring during the immediate (30 min) and the late (6 and 24 h) cutaneous reaction phases were quantitatively analyzed. 24 h after agonist introduction, the recruitment of inflammatory cells on the superficial dermis was studied by use of Rebuck's windows. Histamine release in pollen-containing skin chambers was immediate and persisted until the 24th h despite replacement of the agonists by control medium at the 6th h. An intense PGD2 release occurred as soon as the first 30 min in chambers containing either exogenous histamine or pollen and was maintained until the 24th h. Protein diffusion induced by histamine and pollen was similar to the control one at 30 min but was intensely enhanced at the 6th h. At the 24th h, pollen-induced protein diffusion was still intense whereas that induced by histamine was analogous to the control one. 24 h after pollen challenge, numerous eosinophils were recruited on the superficial dermis but almost none were observed after control medium or histamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Eosinophils↗
PubMed2004

A model of pollen-mediated gene flow for oilseed rape.

The development of genetically modified (GM) crops has precipitated the need for risk assessment and regulation of pollen-mediated gene flow. In response to this need we present a mathematical model to predict the spatial distribution of outcrossing between progenitor populations of oilseed rape. The model combines the processes of pollen dispersal and pollination, resulting from wind and insect activity. It includes the effects of post-pollination reproductive processes by relating the number of progeny to both pollen deposition and competition at the stigma. Predictions compare well with a range of experimental results for different-sized GM source crops (i.e. 0.0064-0.8 ha) and non-GM target crops with different fertilities (i.e. self-fertile to 80% male-sterile). For these comparisons, we represent the variation caused by wind and insect exposure as a constrained set of random functions and limit the range of insect transport to typical plant-scale distances. In addition, the model is used to examine the relative sensitivity to the factors that determine gene flow. Target-crop fertility and source-crop size are shown to be more important than other factors, including background pollen and the natural range of insect activity. The concept of isolation distance to regulate gene flow is most effective for self-fertile target crops, but is ineffective for male-sterile target crops with low background pollen.

Animals↗
PubMed1999

An experimental allergic conjunctivitis induced by topical and repetitive applications of Japanese cedar pollens in guinea pigs.

OBJECTIVE AND DESIGN: To develop a model of experimental allergic conjunctivitis, guinea pigs were given repetitive and topical applications of Japanese cedar pollen as an antigen, and the resulting allergic reaction was characterised. SUBJECTS: Male Hartley guinea pigs. TREATMENT: Guinea pigs were sensitised by insertion of small gelatin sponge pieces (3 pieces/eye, both eyes) containing the pollen extracts + Al(OH)3 into the palpebra superior/inferior sulci of both eyes for 8 h/day for 6 days. Then the animals were challenged by dropping pollen suspension in each eye once every week. METHODS: Time-course changes of conjunctivitis intensity score (CIS), which represents oedema and redness, and scratching frequency, and gamma1 and IgE levels in sera were assessed following the respective 1st-17th challenges. Ophthalmic lavage was performed to assay for albumin leakage and migrated leukocytes at each of the odd-numbered challenges. RESULTS: At relatively early stages of the repeated challenge, only a gradual increase of CIS was observed. However, thereafter, considerably higher CIS with the maximum at 30 min after the challenge was provoked at the 12th-17th challenges. Quite interestingly, there were differences in the CIS between the right and left eyes, depending on the individuals. Scratching, and albumin leakage and neutrophil influx into the lavage fluid were also developed during the challenges. Although the anaphylactic antibodies against the antigen were detected in the sera from half of the animals, the levels were not correlated to severity of the symptoms. CONCLUSIONS: The present sensitisation/challenge procedures are unique in terms of topical application of antigen. The lack of any correlation between the levels of the anaphylactic antibodies and severity of anaphylactic symptoms, and the difference of CIS between the left and right eyes of an individual strongly suggest that the anaphylactic antibodies are formed in locally limited tissue surrounding an eye. The present method should be useful for analysing the mechanisms of allergic conjunctivitis.

Administration, Topical↗
PubMed2005

The impact of host starvation on parasite development and population dynamics in an intestinal trypanosome parasite of bumble bees.

Host nutrition plays an important role in determining the development and success of parasitic infections. While studies of vertebrate hosts are accumulating, little is known about how host nutrition affects parasites of invertebrate hosts. Crithidia bombi is a gut trypanosome parasite of the bumble bee, Bombus terrestris and here we use it as a model system to determine the impact of host nutrition on the population dynamics and development of micro-parasites in invertebrates. Pollen-starved bees supported significantly smaller populations of the parasite. In pollen-fed bees the parasite showed a temporal pattern in development, with promastigote transmission stages appearing at the start of the infection and gradually being replaced by choanomastigote and amastigote forms. In pollen-starved bees this developmental process was disrupted, and there was no pattern in the appearance of these three forms. We discuss the implications of these results for parasite transmission, and speculate about the mechanisms behind these changes.

Animals↗
PubMed2006

Flexible stigma presentation assists context-dependent pollination in a wild columbine.

Stigma presentation has received much less attention than pollen presentation. Investigation of the various forms of stigma presentation may reveal previously undescribed reproductive mechanisms in plants. Here we investigated stigma presentation in the spring-flowering herb Aquilegia yabeana, whose linear stigma gradually develops over the lifetime of the flower. The degree of stigma development and recurvature are influenced by the timing of pollen deposition, apparently to favor cross-pollination. In this species, autogamous self-pollination was found to occur in the middle of the receptive period of the stigma if prior cross-pollination did not occur. However, because later-arriving cross-pollen was deposited closer to the ovary, it reached the base of the style before self-pollen which had been deposited earlier. Flexible stigma presentation helps the flower to maximize pollen resources under unreliable pollination conditions, taking advantage of both selfing and outcrossing. This is the first description of stigma development regulated by pollen deposition in a wild plant.

Aquilegia↗
PubMed2005

An anther- and petal-specific gene SlMF1 is a multicopy gene with homologous sequences on sex chromosomes.

A male flower-specific gene SlMF1 was isolated from male flower buds of the dioecious plant Silene latifolia. SlMF1 is expressed in all the floral meristems at the very early stage of development in both male and female flower buds. At the mature stage of development in male flower buds, SlMF1 transcripts were specifically accumulated in pollen mother cells, tapetal cells, and the developing tips of petals. Genomic Southern hybridization revealed that SlMF1 was a multicopy gene with a Y chromosome-linked homologous sequence. PCR analyses with flow-sorted chromosomes showed that SlMF1 was localized on both autosomes and the X chromosome.

Chromosome Mapping↗
PubMedDate not supplied

Allergy to Parietaria pollen and month of birth.

It has been suggested that the season of birth is a predisposing factor for allergic sensitization. In the last few years many authors in different countries have found a statistically significant correlation between the month of birth and the subsequent allergy for grasses and birch pollens and house dust mites. Nevertheless, other investigators failed to confirm these results. The aim of the present study is to assess the relationship between the season of birth and the development of respiratory allergy to pollen of Parietaria, an Urticacea plant characteristic of Mediterranean flora, which is the most important hay fever producing one in our country. Among the patients who visited the Servizio Autonomo di Allergologia at the St. Martino Hospital (Genoa, Italy) in the year 1986, 264 subjects (113 F and 151 M, 5-35 years of age, all born and living in Genoa and its suburbs) were selected. The birth month of these patients, affected by rhinitis and/or bronchial asthma and with positive prick-test only toward Parietaria pollen, was recorded and compared with that of the population born in Genoa in the same years. Statistical evaluation made by X2 test showed the absence of a statistically significant relationship between the birth in the pollen season (April-July) and the pollinosis, with the exception of the month of May. The reasons of the discrepances observed between the behaviour of Parietaria pollen and that of the other pollens, grasses and birch, described in the above studies, are discussed.

Adolescent↗
PubMed2003

Tapetum determinant1 is required for cell specialization in the Arabidopsis anther.

In flowering plants, pollen formation depends on the differentiation and interaction of two cell types in the anther: the reproductive cells, called microsporocytes, and somatic cells that form the tapetum. The microsporocytes generate microspores, whereas the tapetal cells support the development of microspores into mature pollen grains. Despite their importance to plant reproduction, little is known about the underlying genetic mechanisms that regulate the differentiation and interaction of these highly specialized cells in the anther. Here, we report the identification and characterization of a novel tapetum determinant1 (TPD1) gene that is required for the specialization of tapetal cells in the Arabidopsis anther. Analysis of the male-sterile mutant, tpd1, showed that functional interruption of TPD1 caused the precursors of tapetal cells to differentiate and develop into microsporocytes instead of tapetum. As a results, extra microsporocytes were formed and tapetum was absent in developing tpd1 anthers. Molecular cloning of TPD1 revealed that it encodes a small protein of 176 amino acids. In addition, tpd1 was phenotypically similar to excess microsporocytes1/extra sporogenous cells (ems1/exs) single and tpd1 ems1/exs double mutants. These data suggest that the TPD1 product plays an important role in the differentiation of tapetal cells, possibly in coordination with the EMS1/EXS gene product, a Leu-rich repeat receptor protein kinase.

Amino Acid Sequence↗
PubMed2001

Environmental contributions to allergic disease.

The environment is a major contributor to allergic disease, and great effort is being expended to identify the chemical pollutants and allergens that make a significant impact. Exposure to high levels of ozone, sulfur dioxide, nitrogen dioxide, and diesel exhaust particles is known to reduce lung function. Studies continue to delineate the role of these particles as adjuvants and carriers of allergens into the respiratory system. Current studies also show the exacerbation of allergic disease through fungal spore inhalation and continue to document the role of pollen in allergic rhinitis. Pollen also was recently associated with asthma epidemics, especially after thunderstorms. Forecasting models currently are being developed that predict the trajectories of pollen dispersal and may allow increased avoidance of dangerous outdoor conditions.

Air Pollutants↗
PubMed2005

[QTL analysis of low-temperature-sensitive pollen sterility in Indica-japonica hybrid rice (Oryza sativa L.)].

There existed a number of biological constraints in exploiting the heterosis of indica-japonica hybrid rice. The low-temperature-sensitive sterility (LTSS) of indica-japonica hybrid has become one of the major problems in indica-japonica hybrid rice breeding after the solution of poor fertility of the hybrids by the finding of wide-compatibility gene. Previous studies revealed that the LTSS might be caused by low-temperature-sensitive pollen sterility (LTSPS). However, the genetic basis of LTSPS remained unclear. To explore the genetic basis of LTSPS in indica-japonica hybrid rice, an F2 genetic population derived from 3037 (indica) and 02428 (japonica) was developed. At the booting stage, pollen fertility of F2 population together with parents were surveyed after the treatment with low temperature daily average of 21-23 degrees C. The linkage map was constructed containing 108 SSR markers distributed throughout the whole 12 chromosomes with average marker interval of 16.26 cM. Using software MapMaker/QTL, two putative QTLs, namely qLTSPS2 and qLTSPS5 on chromosomes 2 and 5 were detected by interval mapping, which could explain the phenotypic variation 15.6% and 11.9% respectively. The additive effects were 0.021 and 0.045, dominant effects were -0.246 and -0.215, and the degrees of dominance were 11.7 and 4.8, respectively for the two QTLs. Therefore, the mode of gene action in response to low-temperature stress was overdominance and LTSPS was mainly the result of interaction between the indica and japonica alleles within each locus. In addition, two-way ANOVA showed that the two QTLs acted essentially independent of each other in conditioning LTSPS.

Alleles↗
PubMed2006

Safety and immunological changes during sublingual immunotherapy with standardized quality grass allergen tablets.

Immunotherapy is the only treatment for allergy that has the potential to alter the natural course of the disease. Sublingual immunotherapy for grass pollen-induced rhinoconjunctivitis has been developed to make immunotherapy available to a broader group of allergic patients. Here, a safe dose range and the safety during daily sublingual administration were investigated for a new tablet-based sublingual immunotherapy for grass pollen allergy. Simultaneously, immunological changes were monitored. A randomized, double-blind, placebo-controlled phase I trial was undertaken, with stepwise dose-escalation during the dose-finding period, and afterwards with daily dosing 8 weeks prior to and 15 weeks during the grass pollen season (2500, 25000, or 75000 standardized quality tablet [SQ-T] units, or placebo). Fifty-two participants with grass pollen-induced rhinoconjunctivitis and a positive skin prick test and specific IgE to Phleum pratense entered the trial. During the daily-dose treatment periods, 67% of the participants reported adverse events. The most frequent were itching in the mouth, eyes, or throat, and rhinitis, and most were mild and resolved within 1 day. Two participants withdrew due to adverse events (sting and blisters in the mouth and itching in the mouth). Time- and dose-dependent increases of P pratense-specific IgG, IgA, IgE, and IgE-competing components were found in serum during the first 8 weeks of daily dosing, indicating that the treatment had a significant allergen-specific effect on the immune system. In conclusion, the grass allergen tablet, administered in a dose of 75000 SQ-T once daily, was well tolerated and displayed systemic immunogenicity.

Administration, Oral↗
PubMedDate not supplied

Safety evaluation of a new allergy vaccine containing the adjuvant monophosphoryl lipid A (MPL) for the treatment of grass pollen allergy.

A novel allergy vaccine (Pollinex Quattro) has been developed for the prevention or relief of allergic symptoms caused by a variety of pollens. Within this range, the grass pollen allergy vaccine contains extracts of 12 grass pollens and rye cereal (all chemically modified by glutaraldehyde) that are adsorbed onto L-tyrosine with addition of the immunostimulatory adjuvant monophosphoryl lipid A (MPL). A specific preclinical safety testing strategy was developed to support clinical use, comprising single-dose toxicity, repeat-dose toxicity and local tolerance studies. Dose levels of up to 0.5 ml per animal (mouse) and up to 1.0 ml per animal (rat and rabbit) were used with vaccines containing 2000 or 12 000 standardized units (SU) ml(-1) of grass pollen allergoids, 50 micro g ml(-1) of MPL adjuvant and 20 mg ml(-1) of tyrosine. Overall, the product showed no toxicological findings of significance at levels greatly in excess of those proposed for clinical use. A not unexpected, but relatively minor, immunostimulatory effect was seen following repeated dosing (once weekly for 3 weeks) at 1.0 ml per rat.

Adjuvants, Immunologic↗
PubMed1986

IgE antibody responses against Japanese cedar pollen in the mouse.

IgE antibody responses against Japanese cedar pollen in the mouse were investigated to develop a mouse model of human allergy for combinations of factors including pollen administration routes, elicitation antigens and inbred mouse strains. Daily short term inhalation of native pollen or intratracheal administration of pollen suspended in saline induced IgE antibody responses in DBA/2, BDF1 and Balb/c mice, but failed to induce any detectable responses in C57BL/6 and C57BL/10 mice. Intraperitoneal injection of pollen suspension also induced IgE antibody responses in DBA/2, BDF1 and Balb/c mice but not in C57BL/6 mice. IgE antibody responses against pollen described above were detected by passive cutaneous anaphylaxis (PCA) reactions using crude extract of pollen as an elicitation antigen. On the other hand, IgE antibodies specific for antigen Sugi basic protein (AgSBP), which is a major allergen of pollen in humans (Yasueda, H., Yui, Shimizu, T., and Shida, T., 1983. Isolation and partial characterization of the major allergen from Japanese cedar (Cryptomeria japonica) pollen. J. Allergy Clin. Immunol. 71: 77-86), were also detected by PCA reactions using AgSBP in the sera from mice which received secondary or the tertiary stimulation by pollen. These results suggest that IgE antibody responses against Japanese cedar pollen in the mouse can be induced by airway sensitization and that the responses are genetically controlled by H-2-linked immune response genes. The results also suggest that not only IgE antibody responses specific for components other than AgSBP but also responses specific for AgSBP can be induced in the mouse by repeating appropriate sensitization by pollen.

Administration, Inhalation↗
PubMed1999

Differential ovule development following self- and cross-pollination: the basis of self-sterility in Narcissus triandrus (Amaryllidaceae).

Self-pollination results in significantly lower seed set than cross-pollination in tristylous Narcissus triandrus. We investigated structural and functional aspects of pollen-pistil interactions and ovule-seed development following cross- and self-pollination to assess the timing and mechanism of self-sterility. Ovule development within an ovary was asynchronous at anthesis. There were no significant differences in pollen tube behavior following cross- vs. self-pollination during the first 6 d of growth, regardless of style morph type. Double fertilization was significantly higher following cross- vs. self-pollination. Aborted embryo development was not detected following either pollination type up to seed maturity. Prior to pollen tube entry, a significantly greater number of ovules ceased to develop following self- vs. cross-pollination. These results indicate that self-sterility in N. triandrus operates prezygotically but does not involve differential pollen tube growth typical of many self-incompatibility (SI) systems. Instead, low seed set following self-pollination is caused by a reduction in ovule availability resulting from embryo sac degeneration. We hypothesize that this is due to the absence of a required stimulus for normal ovule development. If this is correct, current concepts of SI may need to be broadened to include a wider range of pollen-pistil interactions.

Journal Article↗
PubMed1979

Structural changes in the pollinated and unpollinated avocado stigma and style.

Structural changes in the pollinated and unpollinated avocado (Persea americana Mill) stigma and style up to 42 h after first opening of the flower were investigated using light and electron microscopy. The pollen tubes grew in the stigma secretion and intercellular substance and initial contact occurred between the plasma membrane of the male and the cuticle and stigma secretion of the female. The pollen tube wall started to develop 15 min after pollination and increased in thickness up to 24 h after pollination. By 18 h after first opening of the flower, starch had disappeared and cell wall thickenings were present in both the pollinated and unpollinated stigma and style. The wall thickenings developed more slowly in the unpollinated than in the pollinated tissue. They contained lipid and were bounded by callose. Degeneration of the cytoplasm of some of the papilla and transmitting tissue cells occurred only following the passage of the pollen tubes and may be of importance in tube nutrition. There was no degeneration in the unpollinated stigma and style and the cytoplasm did not start to lose clarity until 42 h after first opening of the flower.

Cell Wall↗