Special asynchronous dynamometer designed for fast transient phenomena

This paper is focused on measurement of output of the rotary electromechanic machines, i.e. torque and speed. Special attention is paid to the torque measurement under transient phenomena. The paper is also concentrated on the optimization and interference of the designed asynchronous dynamometer. Thanks to the dynamometer it is possible to measure very fast transient phenomena with a very high precision. The mathematical model of the asynchronous machine completed with the mathematical description of the mechanical elements has also been added. Part of this work is focused on parameters identification of the modeled mechanical elements. Selected transient states were simulated with the help of MATLAB and SIMULINK language

Arbuscular mycorrhizal community structure on co-existing tropical legume trees in French Guiana

Aims We aimed to characterise the arbuscular mycorrhizal fungal (AMF) community structure and potential edaphic determinants in the dominating, but poorly described, root-colonizing Paris-type AMF community on co-occurring Amazonian leguminous trees. Methods Three highly productive leguminous trees (Dicorynia guianensis, Eperua falcata and Tachigali melinonii were targeted) in species-rich forests on contrasting soil types at the Nouragues Research Station in central French Guiana. Abundant AMF SSU rRNA amplicons (NS31-AM1 & AML1-AML2 primers) from roots identified via trnL profiling were subjected to denaturing gradient gel electrophoresis (DGGE), clone library sequencing and phylogenetic analysis. Results Classical approaches targeting abundant SSU amplicons highlighted a diverse root-colonizing symbiotic AMF community dominated by members of the Glomeraceae. DGGE profiling indicated that, of the edaphic factors investigated, soil nitrogen was most important in influencing the AMF community and this was more important than any host tree species effect. Conclusions Dominating Paris-type mycorrhizal leguminous trees in Amazonian soils host diverse and novel taxa within the Glomeraceae that appear under edaphic selection in the investigated tropical forests. Linking symbiotic diversity of identified AMF taxa to ecological processes is the next challenge ahead

Responses of arbuscular mycorrhizal fungi to long-term inorganic and organic nutrient addition in a lowland tropical forest

Improved understanding of the nutritional ecology of arbuscular mycorrhizal (AM) fungi is important in understanding how tropical forests maintain high productivity on low-fertility soils. Relatively little is known about how AM fungi will respond to changes in nutrient inputs in tropical forests, which hampers our ability to assess how forest productivity will be influenced by anthropogenic change. Here we assessed the influence of long-term inorganic and organic nutrient additions and nutrient depletion on AM fungi, using two adjacent experiments in a lowland tropical forest in Panama. We characterised AM fungal communities in soil and roots using 454-pyrosequencing, and quantified AM fungal abundance using microscopy and a lipid biomarker. Phosphorus and nitrogen addition reduced the abundance of AM fungi to a similar extent, but affected community composition in different ways. Nutrient depletion (removal of leaf litter) had a pronounced effect on AM fungal community composition, affecting nearly as many OTUs as phosphorus addition. The addition of nutrients in organic form (leaf litter) had little effect on any AM fungal parameter. Soil AM fungal communities responded more strongly to changes in nutrient availability than communities in roots. This suggests that the 'dual niches' of AM fungi in soil versus roots are structured to different degrees by abiotic environmental filters, and biotic filters imposed by the plant host. Our findings indicate that AM fungal communities are fine-tuned to nutrient regimes, and support future studies aiming to link AM fungal community dynamics with ecosystem function

Insights into the evolution of mammalian telomerase: Platypus TERT shares similarities with genes of birds and other reptiles and localizes on sex chromosomes

Background The TERT gene encodes the catalytic subunit of the telomerase complex and is responsible for maintaining telomere length. Vertebrate telomerase has been studied in eutherian mammals, fish, and the chicken, but less attention has been paid to other vertebrates. The platypus occupies an important evolutionary position, providing unique insight into the evolution of mammalian genes. We report the cloning of a platypus TERT (OanTERT) ortholog, and provide a comparison with genes of other vertebrates. Results The OanTERT encodes a protein with a high sequence similarity to marsupial TERT and avian TERT. Like the TERT of sauropsids and marsupials, as well as that of sharks and echinoderms, OanTERT contains extended variable linkers in the N-terminal region suggesting that they were present already in basal vertebrates and lost independently in rayfinned fish and eutherian mammals. Several alternatively spliced OanTERT variants structurally similar to avian TERT variants were identified. Telomerase activity is expressed in all platypus tissues like that of cold-blooded animals and murine rodents. OanTERT was localized on pseudoautosomal regions of sex chromosomes X3/Y2, expanding the homology between human chromosome 5 and platypus sex chromosomes. Synteny analysis suggests that TERT co-localized with sex-linked genes in the last common mammalian ancestor. Interestingly, female platypuses express higher levels of telomerase in heart and liver tissues than do males. Conclusions OanTERT shares many features with TERT of the reptilian outgroup, suggesting that OanTERT represents the ancestral mammalian TERT. Features specific to TERT of eutherian mammals have, therefore, evolved more recently after the divergence of monotremes.Radmila Hrdličková, Jiří Nehyba, Shu Ly Lim, Frank Grützner, Henry R Bose J

Content of fusarium-mycotoxins in some spring barley varieties (artificial and natural infection).

A quantitative immunochemical technique ELISA was used to determine DON content in samples of spring barley varieties inoculated by Fusarium culmorum in 2000 (12 varieties) and 2001 (19 varieties). DON content in the samples from 2000 crop ranged from 5.1 (Forum) to 19.1 ppm (Jersey) with average 9.7 ppm while the range of DON content in 2001 crop was from 1.3 (Madeira) to 8.2 ppm (CI.4196) with average 3.8 ppm. DON content was also determined in another set of 32 samples of spring barley varieties from fields in 24 districts of the CR from 2001 crop and a mycological examination was made using the method of mycologically monitored grains to identify the species of fungal pathogen. ELISA detected DON in all samples of this set; its content ranged from 0.03 to 3.77 ppm, average content was 0.4 ppm, the limit value was exceeded in one sample only. Fusarium graminearum was a prevailing toxicogenic species in spring barley in 2001; its capture coincided with higher levels of DON. It was stated that ELISA and GC were compatible methods for DON determination.A quantitative immunochemical technique ELISA was used to determine DON content in samples of spring barley varieties inoculated by Fusarium culmorum in 2000 (12 varieties) and 2001 (19 varieties). DON content in the samples from 2000 crop ranged from 5.1 (Forum) to 19.1 ppm (Jersey) with average 9.7 ppm while the range of DON content in 2001 crop was from 1.3 (Madeira) to 8.2 ppm (CI.4196) with average 3.8 ppm. DON content was also determined in another set of 32 samples of spring barley varieties from fields in 24 districts of the CR from 2001 crop and a mycological examination was made using the method of mycologically monitored grains to identify the species of fungal pathogen. ELISA detected DON in all samples of this set; its content ranged from 0.03 to 3.77 ppm, average content was 0.4 ppm, the limit value was exceeded in one sample only. Fusarium graminearum was a prevailing toxicogenic species in spring barley in 2001; its capture coincided with higher levels of DON. It was stated that ELISA and GC were compatible methods for DON determination

Acaulospora sieverdingii, an ecologically diverse new fungus in the Glomeromycota, described from lowland temperate Europe and tropical West Africa

From a survey of arbuscular mycorrhizal (AM) fungi in agroecosystems in Central Europe and West Africa, an undescribed species of Acaulospora was recovered and is presented here under the epithet Acaulospora sieverdingii. Spores of A. sieverdingii are 60-80 μm in diam, hyaline to subhyaline to rarely light yellow and have multiple pitted depressions on the outer spore wall similar to those known for A. alpina, A. cavernata, A. paulinae and A. scrobiculata. The pits in A. sieverdingii are tiny and often irregular and resemble small dots (0.8-1.8 μm) or lines (0.5-1.2 x 1.8-2.5 μm). Analyses of the ITS1, 5.8S subunit and ITS2 regions of the rDNA resolved each of the fi ve species in a monophyletic wellsupported clade and indicate that A. sieverdingii is phylogenetically closer to A. paulinae, A. cavernata and A. denticulata than to A. scrobiculata. The new species is common in Central Europe only at altitudes below 800 m asl where, to date, it has been detected in crop rotation systems and grasslands in Poland, Germany, France, Switzerland and Italy. Under these conditions it may co-occur with A. paulinae, A. cavernata, A. scrobiculata and several other Acaulospora spp. A. sieverdingii was also recorded from subtropical and tropical agro-ecosystems and consequently appears to be adapted to ecologically diverse environments

Acaulospora sieverdingii, an ecologically diverse new fungus in the Glomeromycota, described from lowland temperate Europe and tropical West Africa

From a survey of arbuscular mycorrhizal (AM) fungi in agroecosystems in Central Europe and West Africa, an undescribed species of Acaulospora was recovered and is presented here under the epithet Acaulospora sieverdingii. Spores of A. sieverdingii are 60-80 μm in diam, hyaline to subhyaline to rarely light yellow and have multiple pitted depressions on the outer spore wall similar to those known for A. alpina, A. cavernata, A. paulinae and A. scrobiculata. The pits in A. sieverdingii are tiny and often irregular and resemble small dots (0.8-1.8 μm) or lines (0.5-1.2 x 1.8- 2.5 μm). Analyses of the ITS1, 5.8S subunit and ITS2 regions of the rDNA resolved each of the fi ve species in a monophyletic wellsupported clade and indicate that A. sieverdingii is phylogenetically closer to A. paulinae, A. cavernata and A. denticulata than to A. scrobiculata. The new species is common in Central Europe only at altitudes below 800 m asl where, to date, it has been detected in crop rotation systems and grasslands in Poland, Germany, France, Switzerland and Italy. Under these conditions it may co-occur with A. paulinae, A. cavernata, A. scrobiculata and several other Acaulospora spp. A. sieverdingii was also recorded from subtropical and tropical agro-ecosystems and consequently appears to be adapted to ecologically diverse environments