Oak Pollen Research Articles

Cooling in down-slope peat ecosystems due to accelerated glacial melting in Higher Himalaya, India

High-resolution paleoclimate data and numerous instrumental records report that, at higher elevations, Himalayan temperatures over the last ca. 100 years have been rising (Liu and Chen 2000, Thompson et al. 2000). However, many instrumental records from various lower elevation localities are reporting cooler temperatures in recent decades (Balling 2001). This recent cooling trend is not only opposite to the global warming trend but also with the accelerated retreat of the Himalayan glaciers. The effect that warming conditions and melting glaciers have on downslope ecosystems has not been fully explored. Here we present compelling evidence that, over the last 200 years, accelerated glacier retreat and increased melt waters have played a central role in changing the ecology (and perhaps local climate) of downslope sites. The Pinder Valley (~30° 50' 30° 52' N, 78° 47' 78° 51’E) of the Kumaon Higher Himalaya, receives precipitation from the Asian monsoon predominantly during the summer but also during winter seasons. The valley climate is also influenced by hanging glaciers (viz. Sunder Dunga, Pindari, and Kaphni), situated along the valley head. An ~ 125-cm thick peat deposit situated in oak dominated mixed evergreen forest 2650-m altitude, was trenched and continuously sampled at 2-cm intervals. Well-dated multi-proxy paleoclimate record (pollen, diatoms, phytoliths, % organic matter, and magnetic susceptibility) from this peat sequence revealed past ca. 3500year high-resolution climate history of the area. At the beginning of the peat sequence (ca. 3500 to ca. 3300 cal yr BP), the pollen assemblage was almost exclusively represented by conifers suggesting that the regional climate was cool and wet. A sudden increase in the dominance of grass, alder (Alnus nepalensis) and brown oak (Quercus semecarpifolia) pollen at ca. 3300 cal yr BP indicates an abrupt climatic shift towards drier conditions that continued until ca 2300 cal yr BP. The increase in silver fir (Abies pindrow) and other conifers [Himalayan spruce (Picea smithiana) and blue pine (Pinus wallichiana)] at the expanse of grasses, and the first appearance of diatoms ca. 2300 cal yr BP mark the end of the dry period. The progressive decrease in grass pollen for the following ~200 years reveals the improved wetness of climate until ca. 2100 cal yr BP. Variations in our proxy indicators throughout the remainder of the peat sequence suggest a stepwise increase in wetness until the present. A major shift in all of the proxy indicators at ca. 680 cal yr BP (~ 1320 AD) indicates an increase in SW monsoon at 1300 AD, evidence of which is widespread throughout the Asian monsoon region (Morrill et al. 2003). Around this time the once dominant Fragilaria diatoms abruptly diminished to trace abundances, Navicula minima appeared for the first time in the record in relatively high abundances, and epiphytic diatom taxa became more prominent. Circa 1580 to 1730 AD, a substantial cooling was inferred with a reduction to trace levels of the epiphytic proportion of the diatom assemblage and the strong re-appearance of Fragilaria species to abundances of 80 – 90%, not seen before or afterwards in the peat profile. A comparison of the last ~400 years of the peat record with reconstructed spring temperature trend derived from a series of 12 Himalayan tree-ring chronologies (Yadav and Singh 2002) is consistent with our proxy-based inferences from ca. 1600 AD onwards. The high rate of glacier melting over the last few centuries in the Himalayan mountains is a clear demonstration of a warming climate. Our data show that increased glacial meltwaters under this warmer climatic scenario has had a substantial impact on down-slope ecosystems. It appears that the glacial retreats are consistent with the global climate scenario but the resulting melt waters are having localized to regional cooling effects at lower elevation sites over the last few decades.

Purification and Characterization of the Major Oak Pollen Allergen Que a 1 for Component-Resolved Diagnostics Using ImmunoCAP®

Background: The aim of this study was to purify the major oak pollen allergen, Que a 1, to perform biochemical and immunological characterization of the allergen and to develop an experimental native (n) Que a 1 ImmunoCAP®. Methods: Que a 1 was purified from oak pollen extract using affinity chromatography and characterized by SDS-PAGE, two-dimensional (2D) PAGE, mass spectrometry (MS), N-terminal sequencing and specific IgE inhibition on ImmunoCAP. Samples from 16 subjects sensitized to oak pollen were analyzed by ImmunoCAP for IgE reactivity to nQue a 1, and recombinant (r)Bet v 1 and 2 (profilin). They were also studied in IgE immunoblotting. Results: The purity of nQue a 1 was >95%, since a single band was observed on silver-stained SDS-PAGE. The identity was verified by MS analysis, and 2D-PAGE revealed several isoforms. The obtained N-terminal sequence of 50-amino-acid residues from nQue a 1 showed a 58–74% sequence identity with other pathogenesis-related class 10 allergens. Specific IgE inhibition verified a preserved immunoreactivity (70–92% inhibition). All subjects were sensitized to Que a 1 and Bet v 1, and two to profilin. The IgE antibody levels to nQue a 1 were generally lower than to rBet v 1. The obtained results correlated well with IgE immunoblotting. Conclusions: We present a highly purified and extensively characterized preparation of nQue a 1. Que a 1 seems to be an allergen of equal importance in oak pollen as Bet v 1 in birch pollen. An nQue a 1 ImmunoCAP will be useful in component-resolved diagnostics.

Effects of Soils on the Holocene History of Forest Communities, Cape Cod, Massachusetts, U.S.A.

Palynological evidence from a sediment sequence in Owl Pond, Cape Cod, Massachusetts, documents the persistence of an area of oak-white pine dominated vegetation through most of the Holocene. The small size of the basin (1.6 ha) and its small catchment area suggest that it receives most pollen from nearby vegetation and consequently its pollen record can be used to study the history of the surrounding forests. The 10,500-year pollen record showed three main phases of relative vegetational stability. A late-glacial spruce-jack pine forest phase, followed by an early Holocene phase when white pine dominated the landscape while oak and pitch pine became increasingly important. After 9000 yr BP, an oak-dominated forest was established. White pine continued to be an important component of the forest. This pattern is similar to vegetational changes elsewhere in southern New England, except for the relatively high values of pine pollen, which reflect the influence of the sandy glacial soils on Cape Cod. The pollen record from Owl Pond is compared with that from another site on Cape Cod, Duck Pond. Oak pollen values are higher at Owl Pond, but values of pitch pine pollen are higher at Duck Pond for the past 8000 years. Soil type (composition, texture) is judged to be the most important factor in maintaining the differences between the two sites. The results from Owl Pond suggest that mainly through the local control of the substrate, a mosaic of oak-dominated patches of vegetation existed at places on Cape Cod during the Holocene, interspersed within a pitch pine-dominated landscape.

Discriminating fossil evergreen and deciduous Quercus pollen: A case study from the Miocene of eastern China

In palaeopalynology oaks are rarely identified beyond the generic level. In order to recognize fossil evergreen and deciduous oak pollen, we compiled distinguishing criteria from the literature, most under the SEM, on the living oaks. One of the most significant criteria is the nature of the sculpturing under the SEM. Evergreen oak pollen exhibit at least four kinds of sculpturing, viz. rod-like elements, uniformly fine granules, scabrate–verrucate, and rugulate micromorphology. The first two types of sculpturing are mostly limited to the evergreen oaks and can be used to identify fossil evergreen oak pollen, while the last two types can also be seen in many deciduous oaks. On the other hand, deciduous oak pollen grains have relatively uniform sculpturing, with only two types encountered: scabrate–verrucate and rugulate sculpturing. This sculpturing is mainly present in deciduous oaks, despite its occurrence in some evergreen oaks. An absolute discrimination between evergreen and deciduous oak pollen is thus impossible and would require additional evidence in the form of macrofossils. The diagnostic criteria are applied to a Miocene pollen assemblage from Zhejiang Province, eastern China and demonstrate the high diversity of fossil oaks in the vegetation. The fossil pollen includes three morphotaxa of deciduous origin, two morphotaxa of evergreen habit, and three oaks whose habit is uncertain.

Development of <I>Iphiseiodes quadripilis</I> (Banks) (Acari: Phytoseiidae) on Pollen or Mite Diets and Predation on <I>Aculops pelekassi</I> (Keifer) (Acari: Eriophyidae) in the Laboratory

Development and reproduction of Iphiseiodes quadripilis (Banks) were evaluated on single food diets of pollen (Malephora crocea Jacquin [ice plant] or Quercus sp. [oak]), spider mites, [Eutetranychus banksi (McGregor) or Panonychus citri (McGregor) (Acari: Tetranychidae)], or the citrus rust mite Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae). Experiments were conducted in an environmental chamber at 28 degrees +/- 1 degrees C, 14:10 (L:D) daylength, and 45% RH. I. quadripilis completed development and laid viable eggs that subsequently hatched on diets of either ice plant or oak pollen or eggs and motile stages of E. banksi. P. citri was acceptable as prey, but survival of larvae to adults was only 36%, whereas survival on E. banksi, ice plant pollen, and oak pollen was 48, 60, and 68%, respectively. The webbing produced by P. citri seemed to inhibit foraging behavior of I. quadripilis larvae and nymphs. Larvae of I. quadripilis developed only to the second nymphal instar on a diet of P. oleivora alone or water alone. Starved I. quadripilis females and deutonymphs were observed preying on the pink citrus rust mite, Aculops pelekassi (Keifer) (Eriophyidae). During 4-min observation trials, two series of I. quadripilis fed on 1.8 +/- 0.47 and 3.5 +/- 0.45 A. pelekassi motile stages after being starved for 6 and 24 h, respectively. I. quadripilis females did not prey on P. oleivora in arenas containing both rust mite species.

Development of Iphiseiodes quadripilis (Banks) (Acari: Phytoseiidae) on Pollen or Mite Diets and Predation on Aculops pelekassi (Keifer) (Acari: Eriophyidae) in the Laboratory

Development and reproduction of Iphiseiodes quadripilis (Banks) were evaluated on single food diets of pollen (Malephora crocea Jacquin [ice plant] or Quercus sp. [oak]), spider mites, [Eutetranychus banksi (McGregor) or Panonychus citri (McGregor) (Acari: Tetranychidae)], or the citrus rust mite Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae). Experiments were conducted in an environmental chamber at 28° ± 1°C, 14:10 (L:D) daylength, and 45% RH. I. quadripilis completed development and laid viable eggs that subsequently hatched on diets of either ice plant or oak pollen or eggs and motile stages of E. banksi. P. citri was acceptable as prey, but survival of larvae to adults was only 36%, whereas survival on E. banksi, ice plant pollen, and oak pollen was 48, 60, and 68%, respectively. The webbing produced by P. citri seemed to inhibit foraging behavior of I. quadripilis larvae and nymphs. Larvae of I. quadripilis developed only to the second nymphal instar on a diet of P. oleivora alone or water alone. Starved I. quadripilis females and deutonymphs were observed preying on the pink citrus rust mite, Aculops pelekassi (Keifer) (Eriophyidae). During 4-min observation trials, two series of I. quadripilis fed on 1.8 ± 0.47 and 3.5 ± 0.45 A. pelekassi motile stages after being starved for 6 and 24 h, respectively. I. quadripilis females did not prey on P. oleivora in arenas containing both rust mite species.

Modeling of oak pollen dispersal on the landscape level with a mesoscale atmospheric model

We present the extension and application of the mesoscale atmospheric meteorology model METRAS for dispersion of oak pollen. We incorporated functions for pollen emission, pollen viability and pollen deposition into METRAS and simulated pollen dispersal on a scale of up to 200 km. The basis of the simulations is a real landscape structure that includes topography, land use, and the location and size of oak stands. We simulated the oak pollen dispersion of one single oak stand with an estimated annual pollen production of 1 billion pollen grains/m2 forest surface on two exemplary days of the flowering season in 2000. Depending on the meteorological situation of the simulated days, a pollen cloud with about 10 pollen/m3 may extend up to 30 km from the source. Downstream of the oak stand, approximately 1,000 pollen/m2 deposited up to a distance of 25 km, and lower amounts of pollen deposited up to 100 km away. These values of pollen concentration and deposition lay within the range of published field studies. Overall, it is shown that mesoscale atmospheric models are applicable to simulate pollen dispersal on the landscape level.

Using dispersion and mesoscale meteorological models to forecast pollen concentrations

This work describes the results of research into a source-oriented pollen concentration forecasting technique. Tests were conducted using the National Center for Atmospheric Research/ Penn State Fifth Generation Mesoscale Model (MM5), the National Oceanographic and Atmospheric Administration (NOAA) Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT_4) Model combined with the locations of oak trees and their aerial coverage from biogenic emissions land cover database version 3.1 (BELD3). Daily forecasts of pollen concentrations via MM5 and HYSPLIT_4 were made with 30-min increments and tested against 30-min oak pollen data collected by the St. Louis County Department of Health in Clayton, Missouri, for the month of April 2000. Results from these tests show that the combination of MM5 and HYSPLIT_4 with accurate source locations can provide short-term forecasts as indicated by the levels of forecast pollen and actual oak pollen levels, which follow similar profiles for the day. From the 30 individual pollen concentration forecasts, two example forecasts are presented. Additional studies need to be conducted to further validate these results, using an array of pollen collectors. A better understanding of the biology of pollen release is critical to improving these pollen concentration forecasts.

Viability and sunlight sensitivity of oak pollen and its implications for pollen-mediated gene flow

Pollen-mediated gene flow and the male reproductive success of wind-pollinated trees depend on the initial viability of the pollen and the changes that occur in its viability during transport in the atmosphere. The viability of Quercus robur pollen was determined before and during exposure to sunlight by in vitro germination and the fluorescein diacetate reaction (FCR) in 2002 and 2003, respectively. These experiments allowed us to calculate initial pollen viability and pollen sensitivity to sunlight. The germination test revealed a lower initial pollen viability (25–65%) than the FCR (53–92%). Following 9.5 h of irradiation the viability was reduced to 75–100% as determined by the in vitro germination test or to 40–70% as determined by the FCR. The actual values of initial pollen viability and pollen sensitivity to sunlight were used to define a range of values for modelling pollen dispersal using the mesoscale meteorological model METRAS. The deposition patterns of viable pollen varied by as much as a factor of 14 by changing the viability parameters in the range of the observed values. This suggests significant differences in male reproductive success. Variations in initial pollen viability have stronger effects on the gene-flow pattern than do variations in pollen sensitivity to sunlight. In particular, pollen distribution throughout the local environment is shaped by the initial pollen viability, while pollen sensitivity to sunlight mainly influences long-distance pollen dispersal.

Fagales pollen sensitization in a birch-free area: a respiratory cohort survey using Fagales pollen extracts and birch recombinant allergens (rBet v 1, rBet v 2, rBet v 4).

Birch allergy is one of the most common pollinosis in areas where exposure to high levels of birch pollen is common. Little is known about birch sensitivity in areas without birch pollen exposure and reactivity to birch-related species within the Fagales order. the aim was to evaluate Fagales reactivity within a population not exposed to birch pollen using epidemiological, diagnostic, and laboratory approaches by means of extracts and allergenic molecules. A cohort of 5335 respiratory allergic patients was screened by means of skin testing birch, hazel, and oak pollen extracts. Patients were from a birch-free area, but exposed to other Fagales pollen species. A subset of patients was from an intensively cultivated hazel area. A sample of the Fagales allergic population was tested with other Fagales pollen extract (alder, hornbeam, beech, chestnut) and with apple and hazelnut. IgE detection was performed with birch, hazel, oak, apple, and hazelnut extracts, and with Bet v 1, Bet v 2, Bet v 4, and bromelain. IgE immunoblots were performed using birch and hazel extracts. Epidemiological, clinical, and laboratory data were analysed by stratifying the allergic population. Twenty-five percent of the pollen allergic cohort was skin test positive to at least one of the three Fagales species. Combined reactivity to the three species was recorded in 80% of this cohort. Isolated hazel pollen reactivity was recorded in 13.5% of the Fagales allergic patients. Sixty-six percent of these subjects were from the intensively cultivated hazel area. Reactivity to apple and hazelnut was detected by skin test (40%) and IgE reactivity (60%), but only 19% of the positive patients reported symptoms related to at least one of the two foods. Reactivity to Bet v 1 was recorded in 84% of the birch/hazel/oak co-reactivity group, and in 28% of the subjects with the same co-reactivity, but associating a multiple pollen sensitization. IgE to Bet v 2 (50%) and Bet v 4 (23%) panallergens were recorded positive in the latter subset. Bet v 1 prevalence ranged between 48% and 21% among subgroups of patients coming from different areas. Furthermore, an IgE reactivity to hazel-restricted allergenic components was detected among subjects coming from the same area and having a hazel isolated reactivity. Fagales allergy can be found in birch-free areas caused by the exposure to other Fagales species. Birch allergens can be useful for mimicking the allergenic extract, but are also the exclusive tools for a fine diagnostic and epidemiological approach to Fagales pollen allergy. Allergenic molecules from the hazel family will increase the panel of available reagents for the molecule-based approach to allergy diagnosis and therapy.

Quantitative trends in annual totals of five common airborne pollen types (Betula, Quercus, Poaceae, Urtica, and Artemisia), at five pollen-monitoring stations in western Europe

The existence of long-term (20–33 years) trendsin the annual totals of daily airborne pollenconcentrations of five common and/or allergenicwind pollinating taxa was evaluated at fivepollen-monitoring stations in western Europe:Delmenhorst (D), Helmond (NL), Brussels (B),Leiden (NL), and Derby (UK). At all stations,identical or comparable volumetric traps wereused to sample pollen from the air. For grasspollen no increasing or decreasing trends werefound at any station. Trends for birch pollenand oak pollen are increasing, but notsignificant at the stations with the higherannual totals (Delmenhorst and Helmond),probably due to strong year-to-yearfluctuations. At all five stations significantincreasing trends for stinging nettle pollenwere observed. Trends for mugwort pollen aresignificant at all stations, but in differentdirections. Longer periods of observations areneeded to arrive to more definitive conclusionsabout trends in airborne pollenconcentrations.

Modelling start of oak pollen season in different climatic zones in Spain

Quercus pollen and meteorological data for several years from eight sites in Spain have been statistically analysed to select the threshold temperature and calculate the mean heat accumulation for predicting the Quercus pollination start in different climatic areas. The growing degree days method, which assumes the daily temperature varies as a sine wave, was used for heat accumulation calculations. Threshold temperatures between 4 and 12 °C were chosen using linear regression equations forced through the origin and their root mean square error (RMSE) of predicted against the observed dates for each observation site. Above the threshold, the average growing degree days (up to 1999) for the studied years was taken as the predictor value. Results showed a relationship between the selected threshold and elevation and a stronger and statistically significant correlation between threshold and yearly mean temperature, for each site. Regression analysis indicated that the selected threshold and the calculated heat accumulation were optimum for most of the localities. The validity of the results was tested using the meteorological data for the year 2000 as independent variable and this confirmed that there were only a few days difference between the predicted and observed day of the first pollen release for most of the studied localities.

Proposed changes in seasonality of climate during the Lateglacial and Holocene at Lake Zeribar, Iran

Calcareous sediments spanning the last 13 ka from Lake Zeribar, western Iran, were sampled for stable-isotope analysis as a means of augmenting earlier climatic interpretations based on pollen and macrofossils. The Lateglacial period was cold and dry, supporting semi-desert vegetation and highly concentrated lake water. Low evaporation rates due to the cold resulted in long residence times and high lake stands. Durinig the early Holocene, the upland vegetation changed to a pistachio-oak savanna as low temperatures and aridity ameliorated. Lake level dropped in response to increased evapotranspiration. The low oxygen-isotope values of lacustrine calcite during this period are interpreted as a relative increase in the contributioni of winiter moisture rather than overall changes in effective moisture. A gradual increase in oak pollen at ∼7 ka BP signalled the increase in effective moisture to levels similar to those of today. At the same time the δ18O values increased. reflecting a greater percentage of 18O-enriched spring rains. Modern values and seasonal distribution of precipitation were established by 6 ka BP. A short-lived return to winter-only precipitation occuiTed at ∼4.5 ka BP and resulted in a temporary increase in aridity. The covariance among δ13C, carbonate deposition and δ18O values suggests that lake productivity is linked to these seasonal climatic changes.

Pollen analysis of death valley sediments deposited between 166 and 114 ka

Salt Core DV93–1, from Badwater Basin in California's Death Valley, is a nearly complete sedimentary record of mud and evaporite deposits spanning the past 192 ka. Fossil palynomorph assemblages from core depths of 151.8 m (ca. 166 ka) to 103.5 m (ca. 114 ka) have been analyzed as part of a larger study which will eventually include all of core DV93–1. The palynological analysis discussed here reveals four pollen zones between 151.8 m and 103.5 m. Zone 1, the “Cheno‐Am”; zone (151.8 m to 143.5 m depth, 166–154 ka), has high percentages of Chenopodiaceae/Amaranthus (Cheno‐Am) pollen, and is correlative with the end of marine Oxygen Isotope Stage (OIS) 7. Zone 2, the juniper zone (143.5 m to 117.3 m, 154–124 ka), correlates with OIS 6, as evidenced by high percentages of juniper (Cupressaceae) pollen and low percentages of Ambrosia pollen. Equivalent pollen assemblages are found at higher elevations in Death Valley today, where temperatures are 11° C cooler and rainfall is eight times greater. At the top of Zone 2 (124 ka), a simultaneous drop in juniper and increase in oak (Quercus) pollen occurs, followed by a replacement of Artemisia with Ambrosia in Zone 3, the oak zone. This event corresponds to warming associated with Termination II. The estimated age of this warming event is in agreement with the Termination II event visible in the pollen record from nearby Owens Lake (Litwin et al., 1997). Zone 4, the Asteraceae zone (108.8 m to 103.5 m, 119–115 ka), contains higher percentages of Asteraceae and Cheno‐Am pollen, indicating further warming during this time.

POLLEN ANALYSIS OF DEATH VALLEY SEDIMENTS DEPOSITED BETWEEN 166 AND 114 KA

Salt Core DV93-1, from Badwater Basin in California’s Death Valley, is a nearly complete sedimentary record of mud and evaporite deposits spanning the past 192 ka. Fossil palynomorph assemblages from core depths of 151.8 m (ca. 166 ka) to 103.5 m (ca. 114 ka) have been analyzed as part of a larger study which will eventually include all of core DV93-1. The palynological analysis discussed here reveals four pollen zones between 151.8 m and 103.5 m. Zone 1, the “Cheno–Am” zone (151.8 m to 143.5 m depth, 166–154 ka), has high percentages of Chenopodiaceae/ Amaranthus (Cheno–Am) pollen, and is correlative with the end of marine Oxygen Isotope Stage (OIS) 7. Zone 2, the juniper zone (143.5 m to 117.3 m, 154–124 ka), correlates with OIS 6, as evidenced by high percentages of juniper (Cupressaceae) pollen and low percentages of Ambrosia pollen. Equivalent pollen assemblages are found at higher elevations in Death Valley today, where temperatures are 11° C cooler and rainfall is eight times greater. At the top of Zone 2 (124 ka), a simultaneous drop in juniper and increase in oak (Quercus) pollen occurs, followed by a replacement of Artemisia with Ambrosia in Zone 3, the oak zone. This event corresponds to warming associated with Termination II. The estimated age of this warming event is in agreement with the Termination II event visible in the pollen record from nearby Owens Lake (Litwin et al., 1997). Zone 4, the Asteraceae zone (108.8 m to 103.5 m, 119–115 ka), contains higher percentages of Asteraceae and Cheno–Am pollen, indicating further warming during this time.

Late Pleistocene and Holocene pollen stratigraphy at Lago di Vico, central Italy

A new pollen record from Lago di Vico (core V1) provides fundamental new information towards reconstruction of flora and vegetation history in central Italy during the last 90 000 years. The chronological framework is secured by seventeen AMS14C dates, one40Ar/39Ar date and tephra analyses. At the base of the pollen record, i.e. shortly after the40Ar/39Ar date 87 000±7000 B.P., three phases with significant expansion of trees are recorded in close succession. These forest phases, which stratigraphically correspond to St Germain II (and Ognon?) and precede pleniglacial steppe vegetation, are designated by the local names Etruria I, Etruria II and Etruria III. During the pleniglacial, a number of fluctuations of angiosperm mesophilous trees suggest the presence of tree refugia in the area. The lowest pollen concentration values are recorded at ca. 22 000 B.P. which corresponds with other pollen records from the region. The late-glacial is characterized by an expansion in the arboreal pollen curves that is less pronounced, however, than in other pollen profiles from Italy. The Holocene part of the profile is consistently dominated by deciduous oak pollen. No major changes in arboreal pollen composition are recorded but several marked and sudden declines of the tree pollen concentration suggest that the forest cover underwent dramatic changes. Clear evidence for human impact is recorded only when cultivated crops became important which dates to ca. 2630±95 B.P.

The Holocene climatic optimum and pollen records of sapropel 1 in the eastern Mediterranean, 9000–6000 BP

The most recent sapropel in the deep eastern Mediterranean Sea has been deposited between 9 and 6 ka bp. Climate conditions, as revealed by the pollen records of this sapropel in marine cores, were most favorable for temperate deciduous trees, which is in agreement with the inferences from records of peripheral land pollen sites. The abundance of deciduous oak pollen is much higher than that of Artemisia (sage-brush), indicating that annual precipitation in the mid-elevation borderlands was at least 550 mm without summer drought, but more probably in the range 800–1300 mm. The pollen of Pistacia, which formed a savanna at low elevations, is also at its highest abundance and signals the absence of frost in winter, while being capable of withstanding summer drought. The early Holocene therefore appears as the post-glacial climatic optimum with the highest moisture and mildest winters. In southwest Asia, this is also the time of the Neolithic population explosion with incipient domestication of cereals, possibly following natural selection of the ‘tough rachis’ mutation in wheat and barley by the extreme aridity of the preceding Younger Dryas.

Recombinant birch pollen allergens (rBet v 1 and rBet v 2) contain most of the IgE epitopes present in birch, alder, hornbeam, hazel, and oak pollen: A quantitative IgE inhibition study with sera from different populations

Background: Pollen from trees of the order Fagales are important allergen sources in most parts of the world. Clinical, immunochemical, and molecular biology studies indicate that they contain cross-reactive allergens. The major birch pollen allergen, Bet v 1, and birch profilin, Bet v 2, a highly cross-reactive allergen, have been cloned and expressed in Escherichia coli. Objective: The purpose of this study was to demonstrate the presence of allergens in Fagales pollens that share IgE epitopes with recombinant Bet v 1 and Bet v 2 and to determine the percentage of birch, alder, hornbeam, hazel, and oak pollen–specific IgE that can be preabsorbed with rBet v 1 and rBet v 2 from 102 sera of different populations of subjects allergic to Fagales tree pollen. Methods: The presence of rBet v 1– and rBet v 2–homologous allergens in tree pollen extracts was investigated by IgE immunoblot inhibition experiments, and the percentage of tree (birch, alder, hornbeam, hazel, and oak) pollen–specific IgE that was bound by a mixture of rBet v 1 and rBet v 2 was determined by RAST-based quantitative IgE inhibition experiments. The clinical significance of IgE antibody cross-reactivity was studied by skin prick testing with rBet v 1, rBet v 2, and Fagales pollen extracts. Results: Natural birch, alder, hornbeam, hazel, and oak pollen contain allergens that share IgE epitopes with rBet v 1 and rBet v 2. A combination of rBet v 1 and rBet v 2 accounted for 82% of tree pollen–specific IgE on average. Most of the tree pollen–specific IgE was directed against rBet v 1. Conclusion: rBet v 1 and rBet v 2 contain most of the Fagales pollen–specific IgE epitopes and may therefore substitute natural tree pollen extracts not only for diagnosis but also for patient-tailored immunotherapy of tree pollen allergy. (J Allergy Clin Immunol 1998;102:579-91.)

참나무목 화분항원간의 교차반응

Background: The author reviewed 72 cases of Fagales pollinosis diagnosed in allergy clinic of Mary knoll general hospital from Jul. 1995 through May. 1997. Of interest is the fact that most of these patients had positive response for two or more Fagales pollen allergens in skin prick test and the patients who had single allergen were only 1.4%. Furthermore rate of positive response for Beech was 83.3%, although Beech is rare in Korea. Therefore we postulated that cross-reactivity between Fagales pollens. Objectives: The aim of this study was to observe cross-reactivity between Fagales pollens. Materials and methods: The subjects consist of 72 patients with Fagales pollinosis who had been tested by skin prick test and CAP System between Jul. 1995 and Jun. 1997. Correlations between the result of skin test and that of CAP system with 6 Fagales pollen allergens were studied employing the Spearman’s correlation coefficient(Rho). CAP System inhibition tests were performed on 5 of these patients, who had over 3 class of CAP results for Alder and Oak. Results: Most combination showed statistically significant correlations. Moderate values of Rho(0.42 - 0.61) were found with skin test between the Fagales pollens(p<0.001) and high values of Rho(0.64 - 0.92) were found with CAP System score between the Fagales pollens(p<0.001). CAP scores of the Oak pollen were significantly inhibited by the Alder pollen extract, and vice versa. Conclusion: These results demonstrated the cross—reactivity and common antigenicity between the Fagales pollen allergens. The study on identification of common antigen and the effect of cross—reactivity on imunotherapy will be more required.

Development, Survivorship, and Reproduction of Amblyseius largoensis (Acari: Phytoseiidae) on Selected Plant Pollens and Temperatures

Effects of temperature and 4 plant pollens on the development, survivorship, and reproduction of Amblyseius largoensis (Muma) were evaluated. The average egg incubation period at 15, 20, 25, 30, and 35°C was 6.02, 3.26, 2.01, 1.45, and 1.95 d, respectively. The combined larval and nymphal developmental time (mean ± SD) decreased from 11.18 ± 0.55 to 3.21 ± 0.41 d and adult longevity from 39.45 ± 6.24 to 11.91 ± 5.33 d as temperature was increased from 15 to 35°C, respectively. No significant difference in adult longevity was observed when pollens from live oak, Quercus virginiana Miller, castor bean, Ricinus communis L., cattail, Typha domingensis Persoon, and pygmy date palm, Phoenix roebelenii O'Brien, were provided as food at 25°C. Survivorship was >90% when this predator was reared at 5 constant temperatures on 4 plant pollens as food, with the exception of egg hatch at 35°C. The highest intrinsic rate of natural increase ( rm = 0.265) and net reproductive rate ( ro = 19.27)were obtained at 2.5°C compared with the life table parameters derived from the other 4 constant temperatures. When pollens of live oak, castor bean, cattail, and pygmy data palm were provided as single food sources at 25°C, life table parameters indicated that live oak pollen is the most suitable food source, followed by castor bean and cattail pollens.