EVIDENCE FOR METHYL JASMONATE-INDUCED PHLOROTANNIN PRODUCTION IN FUCUS VESICULOSUS (PHAEOPHYCEAE)

The plant growth regulators jasmonic acid and methyl jasmonate (MeJA) have recently been identified in a variety of marine algae; however, their role in these organisms is currently unknown. Here we report that exposure to MeJA, during periods of tidal emergence causes the induction of polyphenolic chemical defenses (the phlorotannins) in two populations of the common rockweed Fucus vesiculosus (Linnaeus). Phlorotannin concentrations were up to 1.6 times higher in the growing apices of F. vesiculosus from both Avery Point (Connecticut, USA) and Roosevelt Inlet (Delaware, USA) within 10–14 days after a single brief exposure to airborne MeJA at concentrations ranging from 5.42 to 542 nM. The timing and magnitude of this induced increase in phlorotannin concentration are similar to that caused by real and simulated herbivory, raising the question of whether jasmonates, or their oxylipin relatives, are natural elements of antiherbivore responses in Fucus , as they are in vascular plants.     

Mould biodiversity in homes I. Air and surface analysis of 130 dwellings

Summary Air and surface sampling to quantify and identify fungi were conducted over a 10-year period in 130 Belgian homes, including flats and houses. Homes were selected based on the medical files of allergic, mostly asthmatic patients to assess possible mould responsibility in the aetiology of the disease. Air sampling was done with Reuter centrifugal air sampler using different sampling times and incubation temperatures to detect mesophilic and thermotolerant or thermophilic fungi. More than 50 genera were detected, withCladosporium, Penicillium andAspergillus being the most common. The main species detected wereAspergillus versicolor, several species ofPenicillium, Cladosporium sphaerospermum andCladosporium herbarum. Surface sampling was conducted concomitant with air sampling. Surfaces with and without visible mould growth were tested equally by Rodac contact plates or swabs. AlthoughCladosporium herbarum was shown to be a common species in indoor environments by air sampling, it was not detected by surface sampling from visible mould growth. This finding suggests that its presence in dwellings is from an outdoor origin and not indicative of indoor proliferation.Aspergillus versicolor, Cladosporium sphaerospermun, andPenicillium chrysogenum were the most common species isolated from surfaces showing visible mould growth.     

Aerial diffusion of phytopathogenic fungi

Summary Aeriobiological studies are essential for understanding the distribution, ecology and deposition patterns of both phytopathogenic and nonpathogenic fungal spores which are carried away from their source. Many spores and conidia are devitalized during aerial transportation as a consequence of being exposed to atmospheric agents. Nonetheless, a sufficient number remain viable, causing infections of various kinds, some of which extremely serious and with an epidemic trend.In order to predict the onset of fungi-induced diseases, it is necessary to be able to determine the inoculum source of the pathogenic agent. As air is the main vector transporting pathogenic fungal spores and conidia, periodical monitoring is required. Thus, having established the critical stages of plant infection, necessary precautionary measures can be undertaken in order to control diseases onset and development.It is therefore necessary to gain a through understanding of spore takeoff and dispersal mechanisms so as to determine how the spores and conidia are transported by air currents onto the plants and how they cause infective impaction. Spores and conidia suspended in the atmosphere can be collected by means of appropriate traps filtering a predetermined amount of air at predetermined time intervals in order to be able to make predictions as to the possibility of plant infection. Volumetric air sampling allows not only to determine the concentration of spores and conidia in a given period of time but also to establish the hours of the day in which they are present in highest concentrations and in which therefore they are more liable to cause infection. This information may be used in estimating the incidence of disease symptoms, the duration of infection and the seriousness of the disease.On the basis of this data, mathematical models for predicting epidemics can be worked out.     

Particle diameter of the airborne microorganisms over Beijing and Tianjin area

Summary This study was aimed at the detection of the Count Medium Diameter (CMD) of airborne bacterial and fungal particles with the Andersen's six-stage viable air-sampler at four sites over Beijing and Tianjin area. The results were as follows: in the first period (1984–1985) the CMDs annual average were 5.6, 6.6, 5.5, 7.1 µm at Xi-Dan, Feng-Tai, Tang-Gu and Huai-Rou respectively. The CMDs annual average of the airborne fungal particles were 3.9 µm at Feng-Tai and Xi-Dan. In the second period (1987–1988), the CMD annual average of airborne bacteria was 7.3, that of airborne fungi was 3.9 µm at Xi-Dan. At Huai-Rou, the CMD of airborne-bacteria was 7.1.     

Jurassic radiolarites in a Tethyan continental margin (Subbetic, southern Spain): palaeobathymetric and biostratigraphic considerations

A region of the pelagic Subbetic basin within the Southern Iberian Continental Margin is studied in lithostratigraphical and biostratigraphical detail. Jurassic radiolarites (Jarropa Radiolarite Formation, Bathonian–Oxfordian) interbedded with shallow-water marine limestones have been recognized. Underlying the radiolarites (Camarena Formation, Bajocian) are oolitic limestones showing shallowing-upward cycles with karstic surfaces on the top, corresponding to deposition on an isolated carbonate platform on volcanic edifices. The Milanos Formation (upper Kimmeridgian–Tithonian), overlying the radiolarites, contains calciclastic strata with hummocky cross-stratification, which indicate outer carbonate ramp deposition. In the Jarropa Radiolarite Formation some calcisiltite strata with hummocky cross-stratification have been found. The bathymetry of the Subbetic Jurassic pelagic sediments, including the radiolarites, is considered as moderate or shallow in depth. We suggest that the pelagic character of the Jurassic sediments in this margin and their equivalents in other Alpine domains is a consequence of distance from the continent (beyond the pericontinental platform) but not necessarily of depositional depth.     

You eat what you find – Local patterns in vegetation structure control diets of African fungus‐growing termites

Fungus‐growing termites and their symbiotic Termitomyces fungi are critically important carbon and nutrient recyclers in arid and semiarid environments of sub‐Saharan Africa. A major proportion of plant litter produced in these ecosystems is decomposed within nest chambers of termite mounds, where temperature and humidity are kept optimal for the fungal symbionts. While fungus‐growing termites are generally believed to exploit a wide range of different plant substrates, the actual diets of most species remain elusive. We studied dietary niches of two Macrotermes species across the semiarid savanna landscape in the Tsavo Ecosystem, southern Kenya, based on carbon (C) and nitrogen (N) stable isotopes in Termitomyces fungus combs. We applied Bayesian mixing models to determine the proportion of grass and woody plant matter in the combs, these being the two major food sources available for Macrotermes species in the region. Our results showed that both termite species, and colonies cultivating different Termitomyces fungi, occupied broad and largely overlapping isotopic niches, indicating no dietary specialization. Including laser scanning derived vegetation cover estimates to the dietary mixing model revealed that the proportion of woody plant matter in fungus combs increased with increasing woody plant cover in the nest surroundings. Nitrogen content of fungus combs was positively correlated with woody plant cover around the mounds and negatively correlated with the proportion of grass matter in the comb. Considering the high N demand of large Macrotermes colonies, woody plant matter seems to thus represent a more profitable food source than grass. As grass is also utilized by grazing mammals, and the availability of grass matter typically fluctuates over the year, mixed woodland‐grasslands and bushlands seem to represent more favorable habitats for large Macrotermes colonies than open grasslands.     

The use of singlebeam echo‐sounder depth data to produce demersal fish distribution models that are comparable to models produced using multibeam echo‐sounder depth

Seafloor characteristics can help in the prediction of fish distribution, which is required for fisheries and conservation management. Despite this, only 5%–10% of the world''s seafloor has been mapped at high resolution, as it is a time‐consuming and expensive process. Multibeam echo‐sounders (MBES) can produce high‐resolution bathymetry and a broad swath coverage of the seafloor, but require greater financial and technical resources for operation and data analysis than singlebeam echo‐sounders (SBES). In contrast, SBES provide comparatively limited spatial coverage, as only a single measurement is made from directly under the vessel. Thus, producing a continuous map requires interpolation to fill gaps between transects. This study assesses the performance of demersal fish species distribution models by comparing those derived from interpolated SBES data with full‐coverage MBES distribution models. A Random Forest classifier was used to model the distribution of Abalistes stellatus, Gymnocranius grandoculis, Lagocephalus sceleratus, Loxodon macrorhinus, Pristipomoides multidens, and Pristipomoides typus, with depth and depth derivatives (slope, aspect, standard deviation of depth, terrain ruggedness index, mean curvature, and topographic position index) as explanatory variables. The results indicated that distribution models for A. stellatus, G. grandoculis, L. sceleratus, and L. macrorhinus performed poorly for MBES and SBES data with area under the receiver operator curves (AUC) below 0.7. Consequently, the distribution of these species could not be predicted by seafloor characteristics produced from either echo‐sounder type. Distribution models for P. multidens and P. typus performed well for MBES and the SBES data with an AUC above 0.8. Depth was the most important variable explaining the distribution of P. multidens and P. typus in both MBES and SBES models. While further research is needed, this study shows that in resource‐limited scenarios, SBES can produce comparable results to MBES for use in demersal fish management and conservation.     

LATEX: A peculiar biological component in airborne particles?

In a study in the USA, latex allergens have beenidentified in airborne particles. Natural rubber(latex) is a product from the plant Heveabrasiliensis and is largely used in the tireindustry. In the vicinity of roads, latex can becomeairborne due to wear-off processes of tires.Sensitisation to latex has been increasing in the lastdecade; an important pathway for the sensitisation ismediated by the airways. It is not known, if thisconcerns mainly laboratory personnel or if this isalso an environmental problem.This study investigated the content of latex inairborne particles in the vicinity of a road withmoderate traffic, in comparison to a control site.Latex was determined in a competitive ELISA based onpolyclonal IgE antibodies. During spring and summer,collected airborne dust was analysed for the contentof protein and latex. Latex concentrations inPM₁₀ in the city were higher than at the controlsite. At both sites, latex levels were significantlylower in PM_2.5 than in PM₁₀.     

Ragweed in the Czech Republic

During the last years, a well documented expansion ofragweed (Ambrosia artemisiifolia L., Ambrosia trifida L.) over the Mediterranean andtemperate Europe has been in progress. The currentdistribution of ragweed plants in the Czech Republicis summarized and the ragweed pollen concentration asmonitored by 12 pollen stations in the country isdiscussed. The present situation in the ragweed pollensensitization among children and adults with pollenallergy in Brno is described. So far no dangerousexpansion of ragweed plants in our country has beenobserved. Ragweed pollen concentration is occasionallysignificant in the Brno station only, other pollenstations are reporting insignificant amounts ofragweed pollen during August-September periods,although there has been a steady increase in ragweedpollen concentration in the Prague area over the lastfive years. Skin prick tests and/or specific IgEmeasurements with ragweed allergen were performed on94 children with pollen allergy in the Brno region in1995 and on 206, 210 and 229 adult allergic patientsin 1995, 1996 and 1997, respectively. Positive skinreaction or positive specific IgE to ragweed was foundin 22% children and in 25% (1995), 19% (1996) and 25% (1997) adults with pollen allergy. It isconcluded that ragweed does not seem to represent anyimminent major threat to the allergic population inthe Czech Republic until now, however, it remains apotentially very dangerous allergen.