Abstract: The increasing mobility of Europeans for business and leisure has led to a need for reliable information about exposure to seasonal airborne allergens during travel abroad. Over the last 10 years or so, aeropalynologic and allergologic studies have progressed to meet this need, and extensive international networks now provide regular pollen and hay-fever forecasts. Europe is a geographically complex continent with a widely diverse climate and a wide spectrum of vegetation. Consequently, pollen calendars differ from one area to another; however, on the whole, pollination starts in spring and ends in autumn. Grass pollen is by far the most frequent cause of pollinosis in Europe. In northern Europe, pollen from species of the family Betulaceae is a major cause of the disorder. In contrast, the mild winters and dry summers of Mediterranean areas favor the production of pollen types that are rarely found in central and northern areas of the continent (e.g., the genera Parietaria, Olea, and Cupressus). Clinical and aerobiologic studies show that the pollen map of Europe is changing also as a result of cultural factors (e.g., importation of plants for urban parklands) and greater international travel (e.g., the expansion of the ragweed genus Ambrosia in France, northern Italy, Austria, and Hungary). Studies on allergen-carrying paucimicronic or submicronic airborne particles, which penetrate deep into the lung, are having a relevant impact on our understanding of pollinosis and its distribution throughout Europe.

Abstract: Successful pollination and fertilization are absolute requirements for sexual reproduction in higher plants. Pollen hydration, germination and penetration of the stigma by pollen tubes are influenced by the exudate on wet stigmas and by the pollen coat in species with dry stigmas. The exudate allows pollen tubes to grow directly into the stigma, whereas the pollen coat establishes the contact with the stigma. Pollen tubes then grow into the papillae, which are covered by a cuticle. The components of the exudate or pollen coat that are responsible for pollen tube penetration are not known. To discover the role of the exudate, we tested selected compounds for their ability to act as functional substitutes for exudate in the initial stages of pollen-tube growth on transgenic stigmaless tobacco plants that did not produce exudate. Here we show that lipids are the essential factor needed for pollen tubes to penetrate the stigma, and that, in the presence of these lipids, pollen tubes will also penetrate leaves. We propose that lipids direct pollen-tube growth by controlling the flow of water to pollen in species with dry and wet stigmas.

Abstract: To separate the effects of heat stress on male and female reproductive tissues, male-sterile (MSs) and male-fertile tomatoes (MFs) were placed in growth chambers at 12 h day/12 h night temperatures of 28/22, 30/24 or 32/26 °C from flower appearance to seed maturation (daily mean temperatures of 25, 27 or 29 °C). Pollen from MFs was applied individually to MS flowers. As MFs were self-pollinated, heat stress was experienced by both male and female tissues. At growth temperatures of 29 °C fruit number, fruit weight per plant, and seed number per fruit were only 10%, 6·4% and 16·4%, respectively, compared with those at 25 °C. Heat stress also adversely affected fruitset in MSs, especially when experienced by donor pollen. No fruit at all developed on MSs receiving pollen produced at 29 °C, even when ovule development, pollen germination and subsequent embryo development all took place at 25 °C. Effects on fruitset in MSs were reduced if donor pollen had not experienced heat stress. MSs grown at 29 °C but receiving pollen developing at 25 °C produced 73% as much fruit (both on number and weight basis), had 40% as high fruitset and produced 87% of the seed per fruit as MSs grown at 25 °C. This use of male-sterile and male-fertile lines of tomato provides new evidence that impairment of pollen and anther development by elevated temperature will be an important contributing factor to decreased fruit set in tomato, and possibly other crops, with global warming.

Abstract: Fossil pollen data supplemented by tree macrofossil records were used to reconstruct the vegetation of the Former Soviet Union and Mongolia at 6000 years. Pollen spectra were assigned to biomes using the plant-functional-type method developed by Prentice et al. (1996). Surface pollen data and a modern vegetation map provided a test of the method. This is the first time such a broad-scale vegetation reconstruction for the greater part of northern Eurasia has been attempted with objective techniques. The new results confirm previous regional palaeoenvironmental studies of the mid-Holocene while providing a comprehensive synopsis and firmer conclusions. West of the Ural Mountains temperate deciduous forest extended both northward and southward from its modern range. The northern limits of cool mixed and cool conifer forests were also further north than present. Taiga was reduced in European Russia, but was extended into Yakutia where now there is cold deciduous forest. The northern limit of taiga was extended (as shown by increased Picea pollen percentages, and by tree macrofossil records north of the present-day forest limit) but tundra was still present in north-eastern Siberia. The boundary between forest and steppe in the continental interior did not shift substantially, and dry conditions similar to present existed in western Mongolia and north of the Aral Sea.

Abstract: Pollen preserved in ice cores from the Dunde ice cap provides a sensitive record of Holocene climatic changes and vegetational response in the northern Qinghai-Tibetan Plateau at time scales ranging from millennia to centuries and decades. Pollen analysis of the annually resolvable ice layers for a 30 yr period (1957‐1986) suggests that total pollen concentration is correlated positively with summer precipitation and negatively with summer temperature; thus it is a sensitive indicator of moisture availability and vegetation density in the steppe and desert regions around Dunde. High pollen concentrations between 10 000 and 4800 yr B.P. suggest that the summer monsoon probably extended beyond its present limit to reach Dunde and westernmost Tibet in response to orbital forcing. The summer monsoon retreated time-transgressively across the Qinghai-Tibetan Plateau during the middle Holocene. Relatively humid periods occurred at 2700‐2200, 1500‐800, and 600‐80 yr B.P., probably as a result of neoglacial cooling. Prominent pollen changes during the Medieval Warm Period (790‐620 yr B.P.) and the Little Ice Age (330‐80 yr B.P.) suggest that the vegetation in the Qinghai-Tibetan Plateau region is sensitive to abrupt, century-scale climatic changes, such as those anticipated in scenarios of greenhouse warming.

Abstract: The quartet (qrt) mutants of Arabidopsis thaliana produce tetrad pollen in which microspores fail to separate during pollen development. Because the amount of callose deposition between microspores is correlated with tetrad pollen formation in other species, and because pectin is implicated as playing a role in cell adhesion, these cell-wall components in wild-type and mutant anthers were visualized by immunofluorescence microscopy at different stages of microsporogenesis. In wild-type, callose was detected around the pollen mother cell at the onset of meiosis and around the microspores during the tetrad stage. Microspores were released into the anther locule at the stage where callose was no longer detected. Deposition and degradation of callose during tetrad pollen formation in qrt1 and qrt2 mutants were indistinguishable from those in wild-type. Enzymatic removal of callose from wild-type microspores at the tetrad stage did not release the microspores, suggesting that callose removal is not sufficient to disperse the microspores in wild-type. Pectic components were detected in the primary wall of the pollen mother cell. This wall surrounded the callosic wall around the pollen mother cell and the microspores during the tetrad stage. In wild-type, pectic components of this wall were no longer detectable at the time of microspore release. However, in qrt1 and qrt2 mutants, pectic components of this wall persisted after callose degradation. This result suggests that failure of pectin degradation in the pollen mother cell wall is associated with tetrad pollen formation in qrt mutants, and indicates that QRT1 and QRT2 may be required for cell type-specific pectin degradation to separate microspores.

Abstract: Foraging and the mechanisms that regulate the quantity of food collected are important evolutionary and ecological attributes for all organisms. The decision to collect pollen by honey bee foragers depends on the number of larvae (brood), amount of stored pollen in the colony, as well as forager genotype and available resources in the environment. Here we describe how brood pheromone (whole hexane extracts of larvae) influenced honey bee pollen foraging and test the predictions of two foraging-regulation hypotheses: the indirect or brood-food mechanism and the direct mechanism of pollen-foraging regulation. Hexane extracts of larvae containing brood pheromone stimulated pollen foraging. Colonies were provided with extracts of 1000 larvae (brood pheromone), 1000 larvae (brood), or no brood or pheromone. Colonies with brood pheromone and brood had similar numbers of pollen foragers, while those colonies without brood or pheromone had significantly fewer pollen foragers. The number of pollen foragers increased more than 2.5-fold when colonies were provided with extracts of 2000 larvae as a supplement to the 1000 larvae they already had. Within 1 h of presenting colonies with brood pheromone, pollen foragers responded to the stimulus. The results from this study demonstrate some important aspects of pollen foraging in honey bee colonies: (1) pollen foragers appear to be directly affected by brood pheromone, (2) pollen foraging can be stimulated with brood pheromone in colonies provided with pollen but no larvae, and (3) pollen forager numbers increase with brood pheromone as a supplement to brood without increasing the number of larvae in the colony. These results support the direct-stimulus hypothesis for pollen foraging and do not support the indirect-inhibitor, brood-food hypothesis for pollen-foraging regulation.

Abstract: Competition for pollination is an important factor structuring flowering in many plant communities. We examined mechanisms reducing interspecific pollen flow in a community of 10 Acacia species in a highly seasonal savannah habitat in Tanzania. Partitioning is achieved, in part, through separation of flowering in space and seasonal time, and through interspecific differences in pollinator guilds. Nevertheless, coflowering Acacia species shared several pollinators; this means that interspecific pollen transfer is possible. We analyzed daily patterns of pollinator activity and pollen release in 10 Acacia assemblages containing a total of 10 Acacia species. Pollinator activity was scored using counts at flowers over constant time intervals throughout the day. Pollen availability was assessed using a simple method which allows quantification of pollen exposed on the surface of the Acacia inflorescence. Sympatric co-flowering Acacia species each show high intra- specific synchrony but release their pollen at different times of day. Pollinators rapidly harvest available pollen and move from one Acacia species to the next, following the daily sequence of pollen release. The activity of shared pollinators is structured throughout the day as a result of temporal patterns of pollen release across Acacia species. The observed temporal structuring of pollen release is compatible with patterns predicted to result from competitive displacement. Additional support for a competition-based explanation for this patterning comes from the observation that an Acacia species flowering without competitors

Abstract: We screened for pollen-specific kinase genes, which are potential signal transduction components of pollen-pistil interactions, and isolated two structurally related receptor-like kinases (RLKs) from tomato, LePRK1 and LePRK2. These kinases are similar to a pollen-expressed RLK from petunia, but they are expressed later during pollen development than is the petunia RLK. The abundance of LePRK2 increases when pollen germinates, but LePRK1 remains constant. Both LePRK1 and LePRK2 are localized to the plasma membrane/cell wall of growing pollen tubes. Both kinase domains have kinase activity when expressed in Escherichia coli. In phosphorylation assays with pollen membrane preparations, LePRK2, but not LePRK1, is phosphorylated, and the addition of tomato style, but not leaf, extracts to these membrane preparations results at least partially in specific dephosphorylation of LePRK2. Taken together, these results suggest that LePRK1 and LePRK2 play different roles in postpollination events and that at least LePRK2 may mediate some pistil response.

Abstract: Background: Pollen from different grass species are some of the most potent elicitors of Type I allergy worldwide. The characterization of antigenic structures and IgE epitopes common to different grass species is relevant to define reagents for diagnosis and specific therapy of grass pollen allergy. Objective: The purpose of this study was to estimate the percentage of IgE directed to common, cross-reactive, or both types of epitopes shared by recombinant pollen allergens (Phl p 1, Phl p 2, Phl p 5, and Bet v 2) and natural pollen extracts from nine different monocots ( Anthoxanthum odoratum, Avena sativa, Cynodon dactylon, Lolium perenne, Phragmites australis, Poa pratensis, Secale cereale, Triticum sativum, Zea mays ) by using sera from different populations. Methods: Natural pollen extracts from nine different monocot species were characterized regarding their allergen contents by using specific antibodies and by IgE immunoblot inhibition with recombinant allergens. The percentage of grass pollen–specific IgE that was preabsorbed with a combination of recombinant timothy grass pollen allergens (Phl p 1, Phl p 2, and Phl p 5) and recombinant birch profilin (Bet v 2) was determined by ELISA in sera from 193 European, American, and Asian subjects. Results: IgE to recombinant pollen allergens accounted for a mean 59% of grass pollen–specific IgE. A lower inhibition of IgE binding to certain natural extracts ( C. dactylon and Z. mays ) could be attributed to the absence of immunologically detectable group 5 and group 2 allergens in these species. Conclusion: We define four recombinant pollen allergens that account for a substantial proportion of grass pollen–specific IgE. The recombinant pollen allergens characterized may represent candidates not only for diagnosis but also for patient-tailored immunotherapy of grass pollen allergy.

Abstract: In order to help establish a basis for the assessment of gene flow associated with the large-scale release of transgenic oilseed rape, we previously designed a method which makes it possible to retrieve the average pollen dispersal of a single plant from that of a large source plot. The ‘individual’ pollen distribution thus obtained is less dependent on the experimental design than pollen distributions usually published and could therefore be used to model the possible escape of a transgene from commercial transgenic crops. In this study we report on a field experiment set up to study the pollen dispersal from an herbicide-resistant transgenic variety of oilseed rape and to test the applicability of the method on the experimental data. Two techniques were used to determine the individual pollen dispersal, and their outcomes are compared. The results suggest that approximately half of the pollen produced by an individual plant fell within 3 m and that the probability of fertilisation afterwards decreased slowly along a negative exponential of the distance. Comparison with the global pollen distribution from the source plot indicates that pollen-dispersal distributions based on dispersal from whole plots instead of individual plants would have underestimated the proportion of pollen that was dispersed over average or long distances.

Abstract: 1. Aspects of the flowering biology of wild cashew Anacardium occidentale, an andro monoecious, self-fertile tree, were studied in the north-east of Brazil, where this species is endemic. Comparison was made among two bee species, Apis mellifera and Centris tarsata, in their pollination of cashew flowers using a number of measures including single bee visits to marked flowers. 2. Cashew flowering is protandrous within a day. Male flowers greatly outnumber hermaphrodite flowers. Stigmas lose receptivity rapidly and pollen is quickly removed from anthers yet flowers remain intact for several days. 3. Only females of C. tarsata collected pollen from cashew flowers, and then only from male flowers. The similar foraging behaviour of the nectar collectors of the two bee species under investigation when visiting hermaphrodite cashew flowers suggests that they may both act as good pollinators. 4. We develop an index of efficiency of pollen removal from anthers (PREi) whereby the relative benefits of flower visitors to a component of a plant’s male reproductive success can be quantified. 5. Comparisons of single bee visits to flowers with unvisited flowers and others receiving unlimited visits were used to show that: C. tarsata pollen collectors were more efficient than nectar collectors of either bee species at removing pollen from anthers; nectar collectors of both bee species had similar pollen removal efficiencies; C. tarsata was more efficient at depositing pollen on stigmas than A. mellifera; both bee species had statistically similar efficiencies at setting seed. 6. The indices of efficiency for some of the stages in the pollination of cashew suggest that C. tarsata flower visits may enhance plant reproductive success over flower visits by A. mellifera but that both bee species may be suitable for the pollination of commercially grown cashew. 7. Despite cashew’s single ovule per flower, high nut set demands a high rate of pollinator visitation during the peak time of stigma receptivity. Provision of additional bee pollination in commercial orchards is recommended to obtain good nut yields.

Abstract: Coleomegilla maculata (DeGeer) is an abundant, polyphagous predator in corn fields; it can develop and reproduce on a diet of only corn pollen. We used sweet corn ( Zea mays L.) in field experiments to investigate the effect of pollen abundance on C. maculata population densities, predation by C. maculata on Helicoverpa zea (Boddie) eggs, and egg cannibalism by C. maculata . Plots designated as "no-pollen plots" were detasseled immediately before anthesis, whereas tassels were left intact in "pollen plots." In both years, when pollen was absent in all plots (i.e., before and after anthesis) there were no significant differences in C. maculata population density, H. zea egg predation, or C. maculata egg cannibalism between pollen and no-pollen plots. During anthesis in 1996, C. maculata egg and larval densities were significantly higher in pollen plots compared with no-pollen plots, but not in 1995. Predation on H. zea eggs was significantly lower in pollen plots than in no-pollen plots in 1995, but not in 1996. During anthesis in both years, egg cannibalism was lower in pollen plots compared with no-pollen plots and significantly so in 1996. Even when abundant pollen led to increased C. maculata larval populations in pollen plots (i.e., in 1996), predation on H. zea eggs and cannibalism of C. maculata eggs was not higher in the pollen plots, suggesting that abundant pollen diverts C. maculata from carnivory. Thus, even though C. maculata populations may increase during anthesis in corn, this increased abundance is not likely to translate into increased predation on H. zea eggs.

Abstract: Background Environmental variation, such as an increase of mean temperature due to the greenhouse effect, as well as the genetic factors may affect the allergenicity of pollen and thus, the prevalence of allergies. The connection between these factors and the allergen content of pollen is poorly understood. Objectives To evaluate the role of environmental and genetic factors on the allergenicity of birch pollen. Methods Mountain birch (Betula pubescens ssp. czerepanovii (Orl.) Hamet-Ahti) pollen was studied using SDS-PAGE and IgE-immunoblotting. Pollen samples were collected from the trees of 10 half-sib families. The study trees from each family were reared in two tree line gardens where the daily mean temperatures were different during the growing season. Results The quantitative analysis of band intensities suggested that the responses of the major birch pollen allergen, Bet v 1, were stronger in the samples collected from the garden with higher daily mean temperature. Half-sib families and individual trees differed in their Bet v 1 content. Conclusions Our results show that both genetic and environmental factors have an effect on the amount of Bet v 1. This suggests that breeding for trees low in allergen content may be possible.

Abstract: Grazed and mown vegetation types in western Norway were investigated with the aim of describing their modern pollen/vegetation relationships as an aid to the interpretation of fossil pollen diagrams. Pollen surface samples and vegetation data were obtained from 186 square metre plots within 39 different sites of 10×10 m. Scatter plots that show the relationship between pollen percentages and vegetation percentages are presented forTrifolium pratense-type,Trifolium rcpens-type,Lotus, Campanula-type,Succisa, Ranunculus acris-type,Cirsium-type, Asteraceae Cichorioideae,Achillea-type,Potentilla-type, Apiaceae,Rumex sect.Acetosa, Galium-type, Cyperaceae,Calluna, Plantago lanceolata and Poaceae. Pollen representation factors relative to Poaceae (Rrel) are calculated for 54 pollen taxa. Differences in the values from different geographical areas were found in the case of some taxa, due to either different genera or species being included in the pollen taxa and/or to the different representation of high pollen producers in the different regional vegetation types. Background pollen influences the estimates for taxa such asR. sect.Acetosa, P. lanceolata, Poaceae, Cyperaceae, andCalluna, and an extended R-value (ERV) model was used to investigate the magnitude of this pollen component. Groups of roughly similar pollen representation were identified and factors to convert pollen percentages to vegetation abundances are suggested.

Abstract: We examined the spatial distribution of maternally inherited mitochondrial DNA and paternally inherited chloroplast DNA polymorphisms in a permanently marked stand of ponderosa pine (Pinus ponderosa Laws). Movement of maternally inherited mtDNA occurs only via seed dispersal, and mtDNA haplotypes showed significant patch structure. Moreover, individuals within patches identified by mtDNA haplotypes were related approximately as half-sibs based upon analysis of allozyme genotypes. Thus, seed dispersal is limited within the population, and creates matrilineal clusters in space. By contrast, paternally inherited cpDNA is dispersed by movement of both seed and pollen. Chloroplast DNA polymorphisms showed no evidence of patch structure, but rather a weak (and nonsignificant) trend toward hyperdispersion, suggesting nearly unlimited movement of pollen among trees within this stand. Two of the trees had unique allozyme alleles, which were used to directly measure pollen movement away from those trees. Marked pollen was as likely to disperse across the population as it was to fertilize near neighbors.

Abstract: 1 We compared modern pollen assemblages from 60 moss polster sites in northern New York with forest composition data within 20–120 m of the sites using extended R-value (ERV) models, which correct for non-linearities arising from use of pollen percentage data. Our sites were concentrated in two regions, one dominated by Tsuga and hardwood (Acer, Betula, Fagus) forests, and the other by Tsuga, Pinus, Betula, Acer and Quercus forests. 2 Our results confirm that forest-floor pollen assemblages are dominated by pollen originating from trees growing more than 20 m from the site of deposition. However, our results suggest that background pollen percentages were overestimated by Jackson & Wong in 1994, owing to unusually high Pinus pollen production in the year of their sampling. 3 Expansion of our vegetation sampling radius from 20 to 120 m resulted in modest but consistent improvement in model fit and a decrease in background pollen percentages. 4 ERV model parameters (slope and background) differed substantially between the two study regions, primarily owing to differences in background pollen productivity and dispersal from regional sources. 5 High background pollen percentages may lead to poor estimation of calibration parameters in regions of complex vegetation patterns. Expansion of the vegetation sampling radius to reduce the background component may lead to better parameter estimates. 6 Calibration of pollen–vegetation relationships requires definition of the vegetation term so that it approximates the vegetation sampled by the pollen assemblages. Critical challenges are to define better the appropriate vegetation sampling area and distance-weighting functions for application to pollen–vegetation calibration.

Abstract: Analysis of pollen spectra from Boriack and Weakly bogs provides a 16,000 year sequence for central Texas. Fluctuations between grass and arboreal pollen indicate that numerous shifts between fores...

Abstract: Hybridization with abundant invaders is a well-known threat to rare native species. Our study addresses mechanisms of hybridization between a rare invader, smooth cordgrass (Spartina alterniflora) and the common native California cordgrass (S. foliosa) in the salt marshes of San Francisco Bay. These species are wind-pollinated and flower in summer. The invader produced 21-fold the viable pollen of the native, and 28% of invader pollen germinated on native stigmas (1.5-fold the rate of the native's own pollen). Invader pollen increased the seed set of native plants almost eightfold over that produced with native pollen, while native pollen failed to increase seed set of the invader. This pollen swamping and superior siring ability by the invader could lead to serial genetic assimilation of a very large native population. Unlike California cordgrass, smooth cordgrass can grow into low intertidal habitats and cover open mud necessary to foraging shorebirds, marine life, navigation, and flood control in channels. To the extent that intertidal range of the hybrids is more similar to the invader than to the native parent, introgression will lead to habitat loss for shore birds and marine life as well to genetic pollution of native California cordgrass.

Abstract: Hybridization with abundant invaders is a well-known threat to rare native species. Our study addresses mechanisms of hybridization between a rare invader, smooth cordgrass (Spartina alterniflora) and the common native California cordgrass (S. foliosa) in the salt marshes of San Francisco Bay. These species are wind-pollinated and flower in summer. The invader produced 21-fold the viable pollen of the native, and 28% of invader pollen germinated on native stigmas (1.5-fold the rate of the native's own pollen). Invader pollen increased the seed set of native plants almost eightfold over that produced with native pollen, while native pollen failed to increase seed set of the invader. This pollen swamping and superior siring ability by the invader could lead to serial genetic assimilation of a very large native population. Unlike California cordgrass, smooth cordgrass can grow into low intertidal habitats and cover open mud necessary to foraging shorebirds, marine life, navigation, and flood control in channels. To the extent that intertidal range of the hybrids is more similar to the invader than to the native parent, introgression will lead to habitat loss for shore birds and marine life as well to genetic pollution of native California cordgrass.

Abstract: Records of different pollen were used to examine associations with weather parameters for the three different pollen: hazel (Corylus sp.), birch (Betula sp.) and grass (Poaceae). As air temperature is expected to rise according to the forecasts from the Intergovernmental Panel on Climatic Change (IPCC) and as this factor has a great potential to affect the development of plants, the records of different pollen were used to understand possible associations. The analysis of weather data for the studied period showed a significant increase in the annual mean temperature. From an aerobiology point of view it is most important to note that the temperature increase in winter (December) becomes most evident. As a consequence of this, hazel started earlier to flower. The flowering period which was originally in March thus shifted to January and February. Therefore the time period for hay fever patients shifted also partly to the traditional winter period. The starting season for birch and grass was not that much ...

Abstract: Seven new male-sterile mutants (ms7-ms13) of Arabidopsis thaliana (L.) Heynh. (ecotype columbia) are described that show a postmeiotic defect of microspore development. In ms9 mutants, microspores recently released from the tetrad appear irregular in shape and are often without exines. The earliest evidence of abnormality in ms12 mutants is degeneration of microspores that lack normal exine sculpturing, suggesting that the MS12 product is important in the formation of pollen exine. Teratomes (abnormally enlarged microsporocytes) are also occasionally present and each has a poorly developed exine. In ms7 mutant plants, the tapetal cytoplasm disintegrates at the late vacuolate microspore stage, apparently causing the degeneration of microspores and pollen grains. With ms8 mutants, the exine of the microspores appears similar to that of the wild type. However, intine development appears impaired and pollen grains rupture prior to maturity. In ms11 mutants, the first detectable abnormality appears at the mid to late vacuolate stage. The absence of fluorescence in the microspores and tapetal cells after staining with 4',6-diamidino-2-phenylindole (DAPI) and the occasional presence of teratomes indicate degradation of DNA. Viable pollen from ms10 mutant plants is dehisced from anthers but appears to have surface abnormalities affecting interaction with the stigma. Pollen only germinates in high-humidity conditions or during in-vitro germination experiments. Mutant plants also have bright-green stems, suggesting that ms10 belongs to the eceriferum (cer) class of mutants. However, ms10 and cer6 are non-allelic. The ms13 mutant has a similar phenotype to ms10, suggesting is also an eceriferum mutation. Each of these seven mutants had a greater number of flowers than congenic male-fertile plants. The non-allelic nature of these mutants and their different developmental end-points indicate that seven different genes important for the later stages of pollen development have been identified.

Abstract: Background: Current diagnostics for grass pollen allergy are composed of mixtures of pollen of different grass species. Their complex composition hampers accurate standardization. Objective: The aim of the study was to investigate whether mixtures of grass pollen extracts can be replaced by a single pollen species and whether a single pollen species can be replaced by a limited number of purified natural or recombinant major allergens. Methods: Sera (n = 800) were selected on the basis of a general suspicion for inhalant allergy and tested in a RAST for IgE reactivity with pollen from 17 different grass species. Cross-reactivity of IgE responses was studied by means of RAST inhibition. Sera with positive test results for grass pollen were tested in a RAST for natural Lol p 1 and Lol p 5 and recombinant Phl p 1 and Phl p 5. Results: Specific IgE antibodies against one or more of the 17 pollen species were detected in 209 of 800 sera (26.1%). The highest responses were observed against Poa pratensis followed by Festuca rubra, Phleum pratense, and Dactylis glomerata. IgE responses were clearly lower (approximately by a factor of 5) against only three species (Phragmites communis, Cynodon dactylon, and Zea mays). With the exception of a few low-responder sera, no sera were found to have negative test results to the high responder species and positive results to any of the other species. Sera with positive test results for grass pollen (n = 154) were tested with purified Lol p 1 and Lol p 5. IgE anti-Lol p 1 and Lol p 5 accounted for an average of 81% ± 7% of total anti-grass pollen IgE. For 14 sera (all with low anti-grass pollen IgE titers), a RAST with purified allergens resulted in a false-negative diagnosis for grass pollen allergy. With recombinant Phl p 1 and Phl p 5, the mean IgE reactivity was 57% ± 6% of the anti-grass pollen IgE response (n = 141), with 13 false-negative results. Conclusion: One grass species is sufficient for in vitro diagnosis of grass pollen allergy. With purified natural Lol p 1 and Lol p 5, greater than 90% of grass-positive sera is detected. Around 80% of the IgE response to grass pollen is directed to these major allergens. Recombinant allergens, produced in Escherichia coli, did not equal the IgE-binding capacity of their natural counterparts. (J Allergy Clin Immunol 1998;102:184-190.)

Abstract: An objective method for the assignment of pollen spectra to appropriate biomes has been published recently. The aim of this paper is to improve the distinction between warm and cool steppes, thus refining vegetation and climate reconstruction, particularly during the Last Glacial Maximum. A set of modern pollen spectra from the Mediterranean and Kazakhstan regions, dominated today by open vegetation types, has been analysed statistically in order to relate pollen taxa abundances to warm acid cool grass/shrub plant functional types (PFTs). A statistical test using modern pollen data shows that the method is able to distinguish between cool and warm steppe biomes with a high degree of confidence. The method has been applied to two fossil pollen records. The results of this exercise showed that cool steppe dominated in central Greece between 18 000 and 13 000 yr BP, while in western Iran the vegetation was at the boundary between cool and warm steppes. These vegetation types were replaced by warm mixed forest in Greece and warm steppe in Iran after that time span. (C) 1998 John Wiley & Sons, Ltd.

Abstract: A simple, quick, and inexpensive method for preparing any type of pollen material is described. Fresh, mature pollen grains without previous chemical fixation are dehydrated in acidified 2, 2-dimethoxypropane (DMP) followed by critical-point drying in CO2. This method helps preserve size, shape and surface details of both fragile pollen grains and pollen grains that are heavily covered with pollenkitt. Handling of already opened anthers and avoiding loss of pollen grains during the preparation steps are also described. With the DMP direct method, many morphologically and functionally important details that may be lost by conventional methods are well preserved without shrinkage, distortion, or dissolution. The DMP direct method is performed with pollen grains and the results are compared with two other frequently used methods, acetolysis and critical-point drying of chemically fixed material.

Abstract: Pollen beetles (Meligethes aeneus) are pests that feed and oviposit in the buds and flowers of oilseed rape. Honey-bees foraging from a hive fitted with an inoculum dispenser at the entrance effectively delivered dry conidia of the entomogenous fungus, Metarhizium anisopliae , to the flowers of oilseed rape in caged field plots. In both winter- and spring-sown rape experiments, a greater mortality of pollen beetles occurred in treated plots than in control plots. The mortality (61% on winter rape, 100% on spring rape) was greatest during peak flowering, when the feeding activity of both bees and beetles from the flowers was maximal, providing optimal conditions for inoculum dissemination and infection. Conidial sporulation occurred on a significant proportion of the dead pollen beetles. There was no evidence of any adverse effect on the honey-bee colonies.