Spatial and temporal variability of macroinvertebrate communities in two farmed Mediterranean rice fields

The spatial and temporal variation of macroinvertebrate assemblages was studied in two Portuguese commercial rice agroecosystems under the effect of field management involving the application of pesticides and fertilizers. A faunal succession of organisms was observed on both fields. Grazers were the first to colonize the paddies after a dry period when pesticides were applied, followed by development into nymphs and by an increase in the abundance of the species after the application of fertilizers. At the end of the season when no pesticides or fertilizers were applied, the communities changed with the presence of adult predators as a result of an increase in prey. Insecticide application revealed specific taxa increase due to the lack of competition with the target organism. Macroinvertebrates tended to prefer infested field margins with aquatic, submerged vegetation, revealing a spatial distribution along the paddies. Two different sampling devices were used and proved necessary in documenting the macroinvertebrate communities (grab for benthic and hand-net for pelagic organisms).     

Is fertility reduced among men exposed to radiofrequency fields in the Norwegian Navy?

The effects of radiofrequency fields on human health are not well understood, and public concern about negative health effects has been rising. The aim of this study was to examine the relationship between workers exposed to electromagnetic fields and their reproductive health. We obtained data using a questionnaire in a cross-sectional study of naval military men, response rate 63% (n = 1487). We asked the respondents about exposure, lifestyle, reproductive health, previous diseases, work and education. An expert group categorized the work categories related to electromagnetic field exposure. We categorized the work categories "tele/communication," "electronics" and "radar/sonar" as being exposed to electromagnetic fields. Logistic regression adjusted for age, ever smoked, military education, and physical exercise at work showed increased risk of infertility among tele/communication odds ratio (OR = 1.72, 95% confidence interval 1.04-2.85), and radar/sonar odds ratio (OR = 2.28, 95% confidence interval 1.27-4.09). The electronics group had no increased risk. This study shows a possible relationship between exposure to radiofrequency fields during work with radiofrequency equipment and radar and reduced fertility. However, the results must be interpreted with caution.     

Combined action of static and alternating magnetic fields on ionic current in aqueous glutamic acid solution

Combined parallel static and alternating magnetic fields cause a rapid change in the ionic current flowing through an aqueous glutamic acid solution when the alternating field frequency is equal to the cyclotron frequency. The current peak is 20-30% of the background direct current. The peak is observed with slow sweep in the alternating magnetic field frequency from 1 Hz-10 Hz. Only one resonance peak in the current is observed in this frequency range. The frequency corresponding to the peak is directly proportional to the static magnetic field. The above effect only arises at very small alternating field amplitude in the range from 0.02 μT-0.08 μT. Bioelectromagnetics 19:41–45, 1998. © 1998 Wiley-Liss, Inc.     

Butterfly diversity at the ecotone between agricultural and semi‐natural habitats across a climatic gradient

Aim Understanding the response of species to ecotones and habitat edges is essential to designing conservation management, especially in mosaic agricultural landscapes. This study examines how species diversity and composition change with distance from semi‐natural habitats, over ecotones into agricultural fields, and how within‐site patterns of community transition change across a climatic gradient and differ between crop types. Location A total of 19 sites in Israel where semi‐natural habitats border agricultural fields (wheat fields or olive groves) distributed along a sharp climatic gradient ranging between 100 and 800 mm mean annual rainfall. Methods  We performed butterfly surveys in 2006. We analysed species richness (α‐diversity), diversity, community nestedness and species turnover (β‐diversity) within sites and between sites (γ‐diversity). We also assessed where species of conservation concern occurred. Results In wheat sites, richness and diversity declined abruptly from ecotones to fields and remained homogenously poor throughout the fields, regardless of climate. In olive sites, despite the sharp structural boundary, richness and diversity remained high from the semi‐natural habitat to the grove margins and then declined gradually into groves. Species of conservation concern occurred across all habitats at olive sites, but none were found inside wheat fields or at their ecotones. The contrast in community structure between semi‐natural habitats and fields was affected by both climate and field type. Irrigation in arid regions did not augment species diversity. Main conclusions Our results indicate that consideration of crop type, within a climatic context, should receive high priority in biodiversity conservation in agricultural areas. In ‘hostile’ crops, such as wheat, we suggest favouring a combination of high‐intensity management and wide margins over less intensive management without margins, which may merely aid generalist butterfly species. The scarcity of butterflies in arid irrigated fields suggests a need to carefully assess the effects of irrigation and agrochemicals on species’ communities.     

Learning generative models for protein fold families

We introduce a new approach to learning statistical models from multiple sequence alignments (MSA) of proteins. Our method, called GREMLIN (Generative REgularized ModeLs of proteINs), learns an undirected probabilistic graphical model of the amino acid composition within the MSA. The resulting model encodes both the position-specific conservation statistics and the correlated mutation statistics between sequential and long-range pairs of residues. Existing techniques for learning graphical models from MSA either make strong, and often inappropriate assumptions about the conditional independencies within the MSA (e.g., Hidden Markov Models), or else use suboptimal algorithms to learn the parameters of the model. In contrast, GREMLIN makes no a priori assumptions about the conditional independencies within the MSA. We formulate and solve a convex optimization problem, thus guaranteeing that we find a globally optimal model at convergence. The resulting model is also generative, allowing for the design of new protein sequences that have the same statistical properties as those in the MSA. We perform a detailed analysis of covariation statistics on the extensively studied WW and PDZ domains and show that our method out-performs an existing algorithm for learning undirected probabilistic graphical models from MSA. We then apply our approach to 71 additional families from the PFAM database and demonstrate that the resulting models significantly out-perform Hidden Markov Models in terms of predictive accuracy.     

Alkaline phosphatase activities of anAnabaena sp. from deep-water rice

Anabaena sp. grew with mono- and di-ester phosphate compounds as sources of phosphate, indicating the presence of phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activities. Cell-bound PMEase and PDEase activities were detected during growth in 0.5 and 10 mg PO₄l^–1 only when the cellular phosphate concentration fell to 0.46% of cell protein and the activities increased as cellular phosphate content decreased. The K_m values for these enzymes were 0.3mm forp-nitrophenyl phosphate and 0.2mm for bis-p-nitrophenyl phosphate, respectively. Only PMEase activity was found extracellularly. The pH optima for PMEase and PDEase were 10.2 and 10.4, respectively, and the temperature optima at pH 10.2 were 37°C and 40°C, respectively. Ca²⁺ increased the enzyme activities while Zn²⁺ caused marked inhibition. The inorganic phosphate repressed the cellular PMEase activity after a lag of 4 h.     

Airborne fungi in vegetable growing areas of Edirne, Turkey

We aimed at the investigation of the airborne fungiand their outdoor incidence in five vegetable growingareas in Edirne province (Turkey) by exposing a petridish with potato dextrose agar medium to air for 15minutes and then counting the number of growingcolonies. Sampling procedure for fungi was performed6 times in research stations at an interval of onemonth between April–September 1996. From the 90petri dishes obtained fungi were isolated and 1166colonies were counted. 12 genera (Absidia,Alternaria, Aspergillus, Botryotrichum, Chlamydomyces,Cladosporium, Endocochlus, Fusarium, Nematochtonus,Penicillium, Trichoderma and Torula) and 25species were identified. Among them, Aspergillusclavato-nanica and Penicillium estinogenum arevery likely to be new records for Turkey. Cladosporium carpophilum and Alternariaalternata were the most abundant species in the studyarea. Correlation analyses were applied to the data.     

Impact of the non-indigenous shrub species Spartium junceum (Fabaceae) on native vegetation in central Spain

Aims The introduction of potentially invasive species through ornamental cultivation or for rehabilitation purposes is a serious environmental problem. They cause damage to biodiversity through loss, increased mortality or ' in situ ' selection phenomena in natural flora. Spartium junceum is a Mediterranean shrub that is not native in most areas of the Iberian Peninsula, although it is extensively grown for the rehabilitation of roadsides. We have investigated the effect on the native vegetation of an old S. junceum (Fabaceae) plantation in a conservation area in the centre of the Iberian Peninsula: the Cuenca Alta del Manzanares nature reserve in Madrid.Methods We compared S. junceum stands with the native nanophanerophytic Cistus ladanifer community at different ecosystem properties: soil properties, temporal soil seed bank contents, standing vegetation and net primary production of annual grasslands growing in these shrublands.Important findings The results highlighted S. junceum 's ability to become established in the new environment (marginal areas of the nature reserve) and ensure its successful growth. This is more apparent in northern and eastern exposures where this formation contacts with the core of the best conserved native vegetation in the nature reserve. Soils under Spartium showed a higher nitrogen content, indicating its capacity—in common with other legumes—to fix N, and conferring an advantage over Cistus, which is N-limited. Other soil nutrients such as phosphorus, magnesium and calcium and water availability are also higher in Spartium soils than in Cistus. Phosphorus is usually a constraint for N-fixers, but in our study, it is the most significant soil variable in both shrub formations and is important to the success of Spartium. Water availability is a key factor for Mediterranean vegetation, and particularly in autumn when soils are recharged. The Spartium formation is able to retain water as its growth produces a closer canopy than Cistus, thereby preventing water evaporation and contributing to the success of this species. Perennials are more frequent in the standing vegetation than in the seed bank, whereas therophytes are similar. The standing vegetation has therophytes and chamaephytes as the predominant growth forms in Spartium sites, and hemicryptophytes and phanerophytes in Cistus. Therophytes are dominant in Spartium and Cistus seed banks, although the first formation has more species. Spartium has a higher number of hemicryptophytes and Cistus is higher in phanerophytes. Northern and eastern aspects show significant differences in richness—with a predominance of annual weed species in Spartium —and in above-ground net primary production, probably as a consequence of the nutrients present in the soils. Ruderal annual species under Spartium (Bromus tectorum, Chenopodium album) have higher germination rates in the greenhouse than in the standing vegetation, suggesting they are at potential risk if environmental conditions change.     

Visual fields,foraging and collision vulnerability in Gyps vultures

The visual fields of vultures contain a small binocular region and large blind areas above, below and behind the head. Head positions typically adopted by foraging vultures suggest that these visual fields provide comprehensive visual coverage of the ground below, prohibit the eyes from imaging the sun and provide extensive visual coverage laterally. However, vultures will often be blind in the direction of travel. We conclude that by erecting structures such as wind turbines, which extend into open airspace, humans have provided a perceptual challenge that the vision of foraging vultures cannot overcome.