Roles of cottony hairs in directed seed dispersal in riparian willows

Willows usually establish on wet substrates with fine sediments at sites that are created by large disturbances, but suitable microsites are spatially and temporally limited. Thus, we hypothesized that willow seeds are selectively dispersed to suitable microsites, such as those with a wet substrate, rather than unsuitable microsites, such as those with a dry substrate, with seedling establishment mediated by the cottony hairs attached to seeds (directed dispersal). To test our hypothesis, we compared several recruitment-related traits, including buoyancy, germination, and trapping at favorable microsites, in seeds of the riparian willows Salix sachalinensis and S. integra with and without cottony hairs in laboratory and field experiments. In both field and laboratory experiments, more seeds with cottony hairs were trapped in water and wet sand than in dry sand, in which no seeds of either species germinated. These results indicate that cottony hairs facilitate the recruitment of seeds to microsites favorable for seed germination and help seeds avoid unfavorable microsites. On the water surface, 17.6% of S. sachalinensis seeds and 68.0% S. integra seeds with cottony hairs floated for more than 6 days, whereas all seeds without cottony hairs sank immediately after being placed on the water surface. These results suggest that cottony hairs facilitate long-distance dispersal via flowing water and also help avoid germination under water, where willow seedlings fail to establish. Seeds of the two willow species were released from the cottony hairs and germinated immediately after the seeds were placed on wet sand, but not after placement on water or dry sand. These results suggest that the seeds are released from the cottony hairs when the hairs become wet and the seeds are striking to a suitable microsite for seedling establishment, such as wet sand. In riparian willows, the cottony hairs promote directed dispersal by moving seeds to discrete and predictable microsites where the seedling establishment is disproportionately high.     

Effect of beetle size on predation of cabbage root fly eggs by ground beetles

Laboratory studies were done to determine the numbers of cabbage root fly (Delia radicum L.) (Diptera: Anthomyiidae) eggs eaten by sixty species of ground beetles (Coleoptera: Carabidae) collected from a range of habitats. For 35 species that were between 2.7 mm and 10 mm long, there was a linear relationship between the numbers of eggs eaten and beetle length. For each 1 mm increase in length above 2.7 mm, an additional 18 eggs were eaten/beetle/day. Eight further species within the above size range did not eat any fly eggs, as these species are known to be either phytophagous or to feed on moving prey. Large numbers of eggs were eaten by beetles in 13 of the 25 genera tested. Based on size, maximum numbers of eggs were eaten by 7 species of Agonum Bonelli, 5 species of Amara Bonelli and seven species of Bembidion Latreille. Only one of the 6 species of Pterostichus Bonelli tested, P. strenuus (Panz.), ate the expected numbers of eggs, the other species being too large to feed from such small prey items as cabbage root fly eggs. The numbers of beetles larger than 10 mm that ate eggs was highly variable and so 10 mm was considered the upper size limit of carabid predators of cabbage root fly eggs.     

Restricted dispersal in a flying beetle assessed by telemetry

Many insects living in ancient trees are assumed to be threatened as a result of habitat loss and fragmentation. It is generally expected that species in habitats with low temporal variability in carrying capacity have lower degree of dispersal in comparison to those in more ephemeral habitats. As hollow trees are long-lived, species in that habitat are expected to be sensitive to habitat fragmentation, due to a low capacity to establish new populations far from present ones. Using radio telemetry, we studied the dispersal for a beetle, Osmoderma eremita, living in hollow trees. O. eremita exhibited philopatry and only dispersed over short ranges. About 82–88% of the adults remained in the tree where they were caught. All observed dispersal movements ended up in nearby hollow trees and 62% in the neighbouring hollow tree. These results corroborate the suggestion that habitat fragmentation may be detrimental to insects living in temporally stable but spatially variable habitats. In order to preserve such species, we propose that conservation efforts should be focused on maintaining or increasing the number of suitable trees in and near presently occupied stands.     

Responses to fertility and disturbance in a low-diversity grassland

We examined variation in species composition in a low-diversity, anthropogenic grassland in response to 11 years of nitrogen (N) manipulation and disturbance. The species-poor grassland (2–3 species/0.5 m²) represents a wide spread vegetation type (>10 million ha in North America) dominated by the introduced perennial grasses Bromus inermis and Agropyron cristatum. Four levels of N and three of soil disturbance were applied in all combinations to plots (5 × 15 m, N = 120) in a completely randomized design each year. Seeds or transplants of 47 species were added to ensure that dispersal was not a barrier to changes in species composition. After 11 years of treatment, all but the most disturbed plots continued to be dominated by B. inermis. The cover of the second-most abundant species, A. cristatum, decreased with disturbance but did not vary significantly with N. Despite the lack of changes in the identity of the dominant species, our environmental manipulations strongly influenced ecosystem characteristics. Added N increased soil available N, and decreased the cover of bare ground and light availability. Soil disturbance decreased aboveground biomass, and increased the cover of bare ground and light availability. Sawdust application, designed to decrease N availability, significantly reduced community biomass, and increased light availability and the cover of bare ground, but did not alter nutrient availability or species composition. The results highlight the difficulty of restoring diversity in species-poor, anthropogenic communities dominated by introduced species, and thus the importance of conserving remnants of diverse natural grasslands.     

Maintenance of high pollen dispersal in Eucalyptus wandoo, a dominant tree of the fragmented agricultural region in Western Australia

Pollen dispersal was investigated in five remnant populations of Eucalyptus wandoo, a dominant insect-pollinated tree in the fragmented agricultural region of southern Western Australia. Paternity analysis using six microsatellite loci identified a pollen source for 45% of seedlings, and the remainder were assumed to have arisen from pollen sources outside the stands. Outcrossing was variable, ranging from 52 to 89%, and long distance pollen dispersal was observed in all populations with up to 65% of pollen sourced from outside the populations over distances of at least 1 km. Modelling dispersal functions for pollination events within the two larger populations showed little difference between the four two-parameter models tested and indicated a fat-tailed dispersal curve. Similarity of direct and indirect historical estimates of gene flow indicates maintenance of gene flow at levels experienced prior to fragmentation. The study revealed extensive long distance pollen dispersal in remnant patches of trees within a fragmented agricultural landscape in the southern temperate region and highlighted the role of remnant patches in maintaining genetic connectivity at the landscape scale.     

Alien seedling recruitment as a response to altitude and soil disturbance in the mountain grasslands of central Argentina

Climate and disturbance are considered key factors in explaining plant invasion, mainly by their effect on alien seedling recruitment. We tested whether soil disturbance by digging and altitude, as a sub-set of climate, affected the seedling recruitment of two alien species (Cirsium vulgare and Melilotus alba) in the mountain grasslands of central Argentina. We performed a seed-addition factorial experiment with altitude as a fixed factor co-variable (6 levels), time since sowing (6 levels) as an autoregressive co-variable, and soil disturbance by digging (two levels) and seed addition (two levels) as fixed factors. Seeds of the studied species were sown in replicated undisturbed and disturbed soil plots, in grassland stands located every 200 m from 1200 to 2200 m a.s.l. The number of emerging seedlings at each plot was recorded during a period of 8 months, at intervals of 30–60 days. Seedlings of both alien species emerged at all the studied altitudes, but only the recruitment of C. vulgare increased linearly with altitude. Moreover, the time window of seedling recruitment for this species increased with altitude. Soil disturbance produced a significant decrease in overall seedling emergence of both species; however, an increase in emergence was observed for C. vulgare at an altitude over 2000 m a.s.l. Natural emergence inside control plots without seed addition was only observed for Cirsium vulgare, which indicates that this species was not seed limited. Our results show that altitude and the absence of disturbance do not restrict the recruitment of C. vulgare and M. alba in these natural mountain grasslands. Moreover, these alien species seem to be tolerant to and even favoured by conditions occurring at higher altitudes and in absence of micro-site soil disturbances in the Córdoba mountain grasslands.     

Fungi associated with the southern pine beetle: avoidance of induced defense response in loblolly pine

Summary Loblolly pines (Pinus taeda) are rapidly killed by colonizing southern pine beetle (Dendroctonus frontalis). The female beetles carry two species of fungi (Ceratocystis minor var. barrasii and an unnamed basidiomycete) within a mycangium. The insects are also frequently associated with a blue-staining form of C. minor. These fungi are inoculated into the tree during colonization. The tree has an induced defensive response that involves resin soaking and necrosis of affected tissue isolating the invading organlsms. The blue-staining fungus stimulates formation of this response in the tree, but the two mycangial fungi do not. These results suggest that the beetles are closely associated with two highly pathogenic fungi that do not stimulate one of the critical components of tree defense.     

Locomotory activity of a visually hunting carabid beetle in response to non-visual prey stimuli

In the predatory beetle Notiophilus biguttatus F. pursuit and attack of prey are induced by visual stimuli associated with prey movement. The study presented in this paper shows that locomotory activity in the predator is affected by prey (springtails — Collembola) previously occupying the relevant substratum. This implies that in prey detection non-visual stimuli are also used. The following effects on locomotion were observed as responses to the cues left by prey: a substantial increase in the frequency of stops and runs and a decrease in the average duration of runs. The adaptive significance of these effects is discussed.Analysis of the experiments includes an evaluation of the statistical powers of the tests used. The estimated powers were used to interpret nonsignificant results.

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Zusammenfassung Die Verfolgung und der Angriff auf eine Beute folgt beim Laufkäfer Notiophilus biguttatus allein auf die visuelle Wahrnehmung bewegender Beutetiere. In der vorliegenden Arbeit wird gezeigt, das die Aktivität des Käfers sich ändert, wenn vorher in seiner Umgebung Beutetiere (Collembolen) anwesend waren. Diese Änderung bedeutet, dass beim Beutefang auch chemische Spuren benützt werden. Dabei wurden folgende Effekte auf die Lokomotion des Käfers festgestelt: eine beträchtliche Zunahme in der Frequenz von Stehenbleiben und Laufen und eine Abnahme der durchschnittlichen Zeitdauer der Läufe. Die adaptive Bedeutung dieser Effekte wird besprochen.Die Experimente wurden einer statistischen power-Analyse unterworfen. Die power-Analyse wurde eingesetzt zur Deutung nichtsignifikanter Ergebnisse und zum Vergleich der Empfindlichkeit verschiedener Aspekte der Lokomotion für den betreffende Reiz.

     

Gas exchange of ears of cereals in response to carbon dioxide and light

One cultivar each of spring wheat (Triticum aestivum L. cv. Arkas), oat (Avena sativa L. cv. Lorenz), and barley (Hordeum vulgare L. cv. Aramir) was chosen in order to study the relative contributions of individual bracts to the gas exchange of whole ears. The distribution and frequency of the stomata on the bracts were examined. Gas exchange was measured at normal atmospheric CO₂ (330 bar) and at high CO₂ (2000 bar) on intact ears and on ears from which glumes or lemmas and pleae (wheat and oat) or awns (barley) had been removed.The relative contribution to the gas exchange of the whole organ is highest for the awns of barley ears. In wheat, the contribution of the glumes is slightly higher than that of the inner bracts before anthesis. Two weeks after anthesis the inner bracts contribute more than the glumes. This tendency of increasing importance of the inner bracts is also found in oat ears, but the relative amount of CO₂ uptake by the glumes is higher than in wheat. These changes during ontogeny result from the better supply of light to the inner bracts caused by opening of the ears' structures during grain filling, which in part compensates for the decreasing photosynthetic capacity.The ratio of the photosynthesis rate at high CO₂ to that at normal CO₂ is lower for the glumes of oat and for the awns of barley than for the other bracts.Abbreviations A³³⁰, A²⁰⁰⁰ net photosynthesis rate, A³³⁰ at normal atmospheric CO₂ (330 bar), A²⁰⁰⁰ at high CO₂ (2000 bar) - PPFD photosynthetic photon flux density - p^c intercellular partial pressure of CO₂     

Proteinase inhibitors I and II in fruit of wild tomato species: Transient components of a mechanism for defense and seed dispersal

The juice of unripe fruit from a wild species of tomato, Lycopersicon peruvianum (L.) Mill., LA 107, contains over 50% of its soluble proteins as the sum of two proteinase inhibitors. These are the highest levels of proteinase inhibitors and highest percentage of soluble proteins as proteinase inhibitors of any plant or animal tissue found to date. Fruit of the modern tomato, L. esculentum Mill., contains only negligible quantities of the two inhibitors. The two proteinase inhibitors in the fruit of L. peruvianum are members of the Inhibitor I and II families previously found in potato tubers and in leaves of wounded potato and tomato plants. The levels of the two inhibitors in the unripe fruit decrease significantly during ripening. Unripe fruit from other wild Lycopersicon species such as L. parviflorum Rick, Kesicki, Fobes et Holle, L. hirsutum Humb. et Bonpe., L. pimpinellifolium Mill., and other lines of L. peruvianum contain moderate levels of the inhibitors that also decrease during ripening. Another wild tomato species, L. pennellii Corr., is similar to L. esculentum in not containing the two proteinase inhibitors in either unripe or ripe fruit. The transient levels of the inhibitors in fruit of wild species indicate that they are present in unripe fruit as defensive chemicals against insects, birds or small mammals and their disappearance during ripening may render them edible to facilitate seed dispersal. High levels of mRNAs coding for Inhibitors I and II in unripe fruit of L. peruvianum, LA 107, indicate that strong promoters may regulate the developmentally expressed proteinase-inhibitor genes in tomato fruit that may have a substantial potential for use in genetic-engineering experiments to enhance the production of large quantities of proteinase inhibitors or other proteins in field tomatoes.Abbreviations poly(A)⁺ mRNA polyadenylated mRNA - SDS-PAGE sodium dodecyl sulfate-polyacrylamide electrophoresis Project 1791, College of Agriculture and Home Economics Research Center, Washington, State University     

Phycomyces: Phototropism and light-growth response to pulse stimuli

The relationship between phototropism and the light-growth response of Phycomyces blakesleeanus (Burgeff) sporangiophores was investigated. After dark adaptation, stage-IVb sporangiophores were exposed to short pulses of unilateral light at 450 nm wavelength. The sporangiophores show a complex reaction to pulses of 30 s duration: maximal positive bending at 3·10^-4 and 10^-1 J m^-2, but negative bending at 30 J m^-2. The fluence dependence for the light-growth response also is complex, but in a different way than for phototropism; the first maximal response occurs at 1.8·10^-3 J m^-2 with a lesser maximum at 30 J m^-2. A hypertropic mutant, L85 (madH), lacks the negative phototropism at 30 J m^-2 but gives results otherwise similar to the wild type. The reciprocity rule was tested for several combinations of fluence rates and pulse durations that ranged from 1 ms to 30 s. Near the threshold fluence (3·10^-5 J m^-2), both responses increase for pulse durations below 67 ms and both have an optimum at 2 ms. At a fluence of 2.4·10^-3 J m^-2, both responses decrease for pulse durations below 67 ms. The hypertropic mutant (madH), investigated for low fluence only, gave similar results. In both strains, the time courses for phototropism and light-growth response, after single short pulses of various durations, show no clear correlation. These results imply that phototropism cannot be caused by linear superposition of localized light-growth responses; rather, they point to redistribution of growth substances as the cause of phototropism.     

Enhancement of phototropic response to a range of light doses in Triticum aestivum coleoptiles in clinostat-simulated microgravity

The phototropic dose-response relationship has been determined for Triticum aestivum cv. Broom coleoptiles growing on a purpose-built clinostat apparatus providing gravity compensation by rotation about a horizontal axis at 2 rev·min^-1. These data are compared with data sets obtained with the clinostat axis vertical and stationary, as a 1·g control, and rotating vertically to examine clinostat effects other than gravity compensation. Triticum at 1·g follows the wellestablished pattern of other cereal coleoptiles with a first positive curvature at low doses, followed by an indifferent response region, and a second positive response at progressively increasing doses. However, these response regions lie at higher dose levels than reported for Avena. There is no significant difference between the responses observed with the clinostat axis vertical in the rotating and stationary modes, but gravity compensation by horizontal rotation increases the magnitude of first and second positive curvatures some threefold at 100 min after stimulation. The indifferent response is replaced by a significant curvature towards the light source, but remains apparent as a reduced curvature response at these dose levels.     

The restoration of gravelly floodplain vegetation and endemic plants to riparian habitat in a Japanese river

Aster kantoensis, an endangered and monocarpic perennial plant species, is endemic to the gravelly floodplain of a few rapid flowing rivers in eastern central Japan. In recent years, an extreme declining trend in the species has been accelerated due to the strong negative influence by invasion of an alien grass, Eragrostis curvula. A restoration project aimed at recovering the original condition of the floodplain in the Kinu River, central Japan, has been started. To determine the possibility of successful restoration as well as its habitat preferences, I carried out some seed sowing experiments. In April 2003, seeds collected from a seminatural habitat were sown (54,000 seeds) in the restoration site (1.2 ha), where flood frequency, substrate condition, and control of alien plants are combined to form different habitat conditions. Seedling survival, flowery, and seed production were subsequently monitored from 2003 to 2005. Seed cohorts completed their life cycles within 3 years, and mean fitness of 927 was achieved. Performance of A. kantoensis seedlings was generally greater for environmental variables of sandy-type substrate and/or with control of alien plants. In addition, there were significant negative correlations between percentage survival, percentage flowery, and seed production with vegetation cover and coverage of E. curvula. The results confirm that, if safe sites with sparse vegetation exist, irrespective of their substrate condition, as well as seed sources of river endemics in natural habitats, restoration of riparian vegetation including river endemics is possible. The aggressive alien species E. curvula should be taken into consideration.     

Habitat models for a riparian carabid beetle: their validity and applicability in the evaluation of river bank management

In order to assess the management success of river rehabilitation measurements it is necessary to have representative target species and objective statistical methods. In this study we, tested the validity of habitat suitability models for the riparian carabid beetle Bembidion velox in the evaluation of river bank management along the River Elbe, Germany. On the basis of seven independent data sets from different sites and years we have proven the robustness of logistic regression models with respect to their explanatory and predictive power and their applicability in the field. All models had robust explanatory power and described a strong association of B. velox with semi-terrestrial sandy open soil habitats. Transfers of model results for adult beetles to their larvae and vice versa were highly significant with “sand content” and “stem distance” as the main habitat factors for both life stages. To broaden the local explanatory power towards general predictions we performed model cross-validation in space and time. Spatial transfers produced models with excellent discrimination properties, measured by Area Under Curve (AUC) values of Receiver Operating Characteristics (ROC) plots, independent of sampling designs and trapping methodology. However, the applicability of habitat models for B. velox is defined by the validity period, as the availability of suitable habitats for this species is highly temporally variable and dependent on water level. Model transfers between species also demonstrated that the chosen target species is representative for carabids with similar distribution patterns, as the single species model had high predictive power for the occurrence of a multi-species carabid group.     

Nutrient enrichment promotes survival and dispersal of drifting fragments in an invasive tropical macroalga

The effect of nutrient availability on growth, survival, and photosynthetic performance of drifting fragments of the invasive red alga Hypnea musciformis was studied in Maui (Hawaii), where this species smothers native reef communities and forms localized blooms. H. musciformis does not sexually reproduce in Hawaii and drifting fragments represent the only pathway by which H. musciformis can disperse and invade new areas. Growth rates decreased with age and approached zero when fragments aged 32 days. Increased nutrient availability did not result in increased relative growth rates during this period. In contrast to growth, photosynthetic performance remained unaffected through time and showed no clear relationship with nutrient availability. Increased nutrient availability increased fragment survival and fragments survived for >2 months in the high nutrient treatment (3.0 μmolPO₄ + 30.0 μmolNH₄). This indicates that increased nutrient availability increases the dispersal potential of H. musciformis. Low growth rates of drifting Hypnea fragments increased recruitment success since attachment success of this epiphytic species decreased with increasing fragment size. H. musciformis thus uses resources for survival and maintenance rather than growth, resulting in long competency periods and optimal recruitment, which likely contribute to its success as an invader of Hawaiian reef communities.     

cDNA cloning of an extracellular dermal glycoprotein of carrot and its expression in response to wounding

Suspension-cultured cells of carrot (Daucus carota L.) synthesize and secrete a glycoprotein that is normally found only in dermal tissues (epidermis, endodermis and periderm). This protein, previously called GP57, is now referred to as EDGP (E xtracellular D ermal G lyco P rotein). We purified sufficient quantities of EDGP to obtain amino-acid sequences on two internal tryptic peptides and screened a cDNA library of young carrot roots with antiserum to EDGP and with oligonucleotides corresponding to the peptides. Here we report the derived amino-acid sequence of EDGP. Sequence comparisons show that it has 40% amino-acid sequence identity with 7S basic globulin, a protein that is released when soybean seeds are soaked in hot water for a few hours. We suggest that these two proteins belong to a new family of dermal proteins. As far as we know, this is the first reported derived amino-acid sequence for protein that is specific to the epidermis and other dermal tissues. The level of EDGP mRNA is low in dry seeds, but increases rapidly in growing seedlings as they develop dermal tissues. The level of mRNA is low in storage roots, but increases rapidly in response to wounding. The presence of EDGP in dermal tissues and its up-regulation in response to wounding indicate a role in the response of plants to biotic and-or abiotic stresses. An unusual feature of the amino-acid sequence of EDGP is that it contains a short motif, which is present at the active site of aspartyl proteases such as pepsin and chymosin.Abbreviations cDNA copy DNA - 2,4-D 2,4-dichlorophen-oxyacetic acid - EDGP extracellular dermal glycoprotein - 7SBG 7S basic globulin Supported by a contract from the United States Department of Energy (Energy Biosciences) (to M.J.C.) and a Grant-in-Aid for Special Research on Priority Areas (01660002, Cellular and Molecular Basis for Reproductive Processes in Plants) from the Ministry of Education, Science and Culture, and by the Fund from Basic Research Core System of Science and Technology Agency, Japan (to S.S.).     

Size-biased dispersal prior to breeding in a damselfly: conflicting evidence from a natural population

Summary The sizes of adult damselflies (Coenagrion puella) that were marked at emergence and recaptured as mature adults at the natal pond and at the next nearest pond were compared. In addition the sizes of a much larger sample of animals that were never recaptured were compared with those that returned to breed at the natal pond. There was no statistically significant difference in mass or wing length between adults in either comparison. This result contrasts with a previous study on a coenagrionid species in which, from an equally small sample, some evidence of size-biased dispersal was detected (dispersing adults were larger than those returning).     

Induction of a cytosolic pyruvate kinase 1 gene during the resistance response to Tobacco mosaic virus in Capsicum annuum

Hot pepper (Capsicum annuum L. cv. Bugang) plants exhibit a hypersensitive response (HR) upon infection by Tobacco mosaic virus (TMV) pathotype P₀. Previously, to elucidate molecular mechanism that underlies this resistance, hot pepper cv. Bugang leaves were inoculated with TMV-P₀ and genes specifically up-regulated during the HR were isolated by microarray analysis. One of the clones, Capsicum annuum cytosolic pyruvate kinase 1 (CaPK _c 1) gene was increased specifically in the incompatible interaction with TMV-P₀. The expression of CaPK _c 1 gene was also triggered not only by various hormones such as salicylic acid (SA), ethylene, and methyl jasmonate (MeJA), but also NaCl and wounding. These results suggest that CaPK _c 1 responds to several defense-related abiotic stresses in addition to TMV infection. The nucleotide sequence data reported in this paper were submitted to the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession number DQ114474.     

Dynamic reorganization of microtubules and microfilaments in flax cells during the resistance response to flax rust infection

The cytoskeleton in plant cells is a dynamic structure that can rapidly respond to extracellular stimuli. Alteration of the organization of microtubules and actin microfilaments was examined in mesophyll cells of flax, Linum usitatissimum L., during attempted infection by the flax rust fungus, Melampsora lini (Ehrenb.) Lev. Flax leaves that had been inoculated with either a compatible (yielding a susceptible reaction) or an incompatible (yielding a resistant reaction) strain of M. lini were embedded in butyl-methylmethacrylate resin; sections of this material were immunofluorescently labelled with anti-tubulin or anti-actin and examined using confocal laser scanning microscopy. In uninfected leaves, microtubules in the mesophyll cells formed a transverse array in the cell cortex. Microfilaments radiated through the cytoplasm from the nucleus. In an incompatible interaction, microtubules and microfilaments were extensively reorganized in mesophyll cells that were in contact with fungal infection hyphae or haustorial mother cells before penetration of the cell by the infection peg. After the initiation of haustorium development, microtubules disappeared from the infected cells, and growth of the haustoria ceased. In an incompatible interaction, hypersensitive cell death occurred in more than 70% of infected cells but occurred in less than 20% of cells in compatible interactions. After the infected cell had undergone hypersensitive cell death, the cytoskeleton in neighbouring cells became focused on the walls shared with the necrotic cell. In compatible interactions, reorganization of the cytoskeleton was either not observed at all or was observed much less frequently up to 48 h after inoculation.Abbreviations FITC fluorescein isothiocyanate - WGA wheatgerm agglutinin We thank Dr. G.J. Lawrence for providing valuable discussions and materials.     

Expression of engrailed in embryos of a beetle and five dipteran species with special reference to the terminal regions

The engrailed expression in embryos of a beetle, four midges and a fly has been analysed with special reference to the terminal regions. In all six species the segmental expression pattern is very similar but variability occurs in the clypeolabrum, foregut and hindgut. In some cases, segmental engrailed expression seems to be extended into the hind- and/or foregut. The engrailed expression of these species is compared with published data from other insects. Correspondence to: U. Schmidt-Ott