1,267 research outputs found

    Ant litter fauna of forest, forest edges and adjacentgrassland in the Atlantic rain forest region of Bahia, Brazil

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    The litter ant fauna was sampled by Winkler sacks and pitfall traps along transects running through Atlantic rain forest into an adjacent grassland. Transects ran 65 m into the forest and 45 m into the field. Ninety-seven species of ants were sampled and scored, 85 were found in the forest, 48 were found in the field and 36 were common to both habitats. There was some evidence that species richness was lowest in the field and high at the deepest point within the forest. The composition of the ant community at the different distances into the forest and field was analysed by a number of hierarchical clustering procedures and also by ordinating the data in three-dimensional space. A two-way table of the ant assemblages derived from the clustering procedure versus the groupings of transect distances obtained by the same procedure indicated that certain ant species had preferences for the field or particular distances into the forest. It is concluded that although the ant fauna of Atlantic rain forest is severely affected by clearing, a forest-like ant fauna is able to persist right up to the interior edge of the forest

    The role of isotope mass and transport for H-mode access in tritium containing plasmas at JET with ITER-like wall

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    Special Issue Featuring the Invited Talks from the 48th EPS Conference on Plasma Physics, 27 June - 1 July 2022The required heating power, , to access the high confinement regime (H-mode) in tritium containing plasmas is investigated in JET with ITER-like wall at a toroidal magnetic field of T and a plasma current of MA. , also referred to as the L-H power threshold, is determined in plasmas of pure tritium as well as mixtures of hydrogen with tritium (H-T) and mixtures of deuterium with tritium (D-T), and is compared to the L-H power threshold in plasmas of pure hydrogen and pure deuterium. It is found that, for otherwise constant parameters, is not the same in plasmas with the same effective isotope mass, , when they differ in their isotope composition. Thus, is not sufficient to describe the isotope effect of in a consistent manner for all considered isotopes and isotope mixtures. The electron temperature profiles measured at the L-H transition in the outer half of the radius are very similar for all isotopes and isotope mixtures, despite the fact that the L-H power threshold varies by a factor of about six. This finding, together with the observation of an offset linear relation between the L-H power threshold, , and an effective heat diffusivity, , indicates that the composition-dependent heat transport in the low confinement mode (L-mode) determines, how much power is needed to reach the necessary electron temperatures at the edge, and hence PLH.This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No. 101052200—EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. G Birkenmeier received funding from the Helmholtz Association under Grant No. VH-NG-1350Peer Reviewed"Article signat per 50 autors/es: G Birkenmeier, E R Solano, I S Carvalho, J C Hillesheim, E Delabie, E Lerche, D Taylor, D Gallart, M J Mantsinen, C Silva, C Angioni, F Ryter, P Carvalho, M Fontana, E Pawelec, S A Silburn, P Sirén, S Aleiferis, J Bernardo, A Boboc, D Douai, P Puglia, P Jacquet, E Litherland-Smith, I Jepu, D Kos, H J Sun, A Shaw, D King, B Viola, R Henriques, K K Kirov, M Baruzzo, J Garcia, A Hakola, A Huber, E Joffrin, D Keeling, A Kappatou, M Lennholm, P Lomas, E de la Luna, C F Maggi, J Mailloux, M Maslov, F G Rimini, N Vianello, G Verdoolaege, H Weisen, M Wischmeier and JET Contributors"Postprint (published version

    Epigaeic ants ina forest remnant in the state of Acre, Brazil and new records for the state.

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    Ants are considered an important group of invertebrates in terrestrial ecosystems, where they participate in important ecological processes between animals and plants, and they are considered good indicators of environmental impacts as well. Although the diversity of ants in the Amazon biome is already relatively well known, the ant fauna in the state of Acre, Brazil is still poorly known. The aim of this study was to carry out a survey of ants in a forest remnant located in the municipality of Plácido de Castro, Acre, using pitfall traps. Thirty-six species of ants were collected from six subfamilies and 18 genera. From the species confirmed, 11 (Cephalotes serraticeps, Gnamptogenys moelleri, Gnamptogenys triangularis, Neoponera apicalis, Neoponera commutata, Neoponera verenae, Mayaponera constricta, Megalomyrmex emeryi, Pachycondyla impressa, Pheidole araneoides and Odontomachus caelatus) are first records for Acre state, increasing our knowledge of the epigaeic ants that occur in this region of the Amazon. As formigas são consideradas um significante grupo de invertebrados nos ecossistemas terrestres, participando de importantes processos ecológicos entre animais e plantas, além de serem consideradas como bons indicadores de impactos ambientais. Apesar de a diversidade de formigas no bioma Amazônico já ser relativamente bem conhecida, a fauna de formigas do estado do Acre ainda é incipientemente estudada. O objetivo deste estudo foi realizar um levantamento de formigas em um remanescente florestal localizado no município de Plácido de Castro - Acre, utilizando armadilhas do tipo "pitfall trap". Foram coletadas 36 espécies de formigas, pertencentes a seis subfamílias e 18 gêneros. Das espécies confirmadas, 11 (Cephalotes serraticeps, Gnamptogenys moelleri, Gnamptogenys triangularis, Neoponera apicalis, Neoponera commutata, Neoponera verenae, Mayaponera constricta, Megalomyrmex emeryi, Pachycondyla impressa, Pheidole araneoides e Odontomachus caelatus) representam primeiros registros para o estado do Acre, aumentando o conhecimento acerca das formigas epigeias que ocorrem nesta região da Amazônia

    Rediscovery and reclassification of the dipteran taxon Nothomicrodon Wheeler, an exclusive endoparasitoid of gyne ant larvae

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    The myrmecophile larva of the dipteran taxon Nothomicrodon Wheeler is rediscovered, almost a century after its original description and unique report. The systematic position of this dipteran has remained enigmatic due to the absence of reared imagos to confirm indentity. We also failed to rear imagos, but we scrutinized entire nests of the Brazilian arboreal dolichoderine ant Azteca chartifex which, combined with morphological and molecular studies, enabled us to establish beyond doubt that Nothomicrodon belongs to the Phoridae (Insecta: Diptera), not the Syrphidae where it was first placed, and that the species we studied is an endoparasitoid of the larvae of A. chartifex, exclusively attacking sexual female (gyne) larvae. Northomicrodon parasitism can exert high fitness costs to a host colony. Our discovery adds one more case to the growing number of phorid taxa known to parasitize ant larvae and suggests that many others remain to be discovered. Our findings and literature review confirm that the Phoridae is the only taxon known that parasitizes both adults and the immature stages of different castes of ants, thus threatening ants on all fronts.Peer reviewe

    Structural Stability of Ant-plant Mutualistic Networks Mediated by Extrafloral Nectaries: Looking at the Effects of Forest Fragmentation in the Brazilian Amazon

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    Rainforest fragmentation drastically affects biodiversity and species composition, mainly due to habitat loss. Several studies have already shown the effects of forest fragmentation on plant and ant communities. To date, however, there is limited empirical knowledge of how forest fragmentation affects ant-plant interaction in networks. We investigated the effects of the configuration of rainforest fragments on the structure of ant-plant interaction networks mediated by extrafloral nectaries (EFNs). We carried out this study in ten forest fragments, ranging in size from approximately 5 to 3,000 ha, located in the Brazilian Amazon. In each fragment we established a plot of 6,250 m2, in which all ant-plant interactions were recorded, and calculated the following network descriptors: number of interactions, network size, network specialization, diversity of interactions, and nestedness. We used four explanatory variables to investigate the effects of forest fragmentation on these network descriptors: three metrics of the configuration of fragments (i.e., fragment area, edge irregularity, and connectivity) and the forest structure within each fragment, represented by canopy cover. We did not detect any effect of the explanatory variables on the network descriptors. The structural stability of the networks sampled in forest fragments with different configurations is possibly related to the observed constancy of ant species in the central core of highly interacting species. Our results corroborate other studies highlighting the structural stability of these facultative ant-plant networks mediated by EFNs in different spatial and temporal gradients. Nonetheless, the low constancy of plant species in the generalist core should be understood as a warning, mainly because the functionality of this protective mutualism (i.e., food secretions in exchange for protection against herbivory) remains unknown

    Alternative splicing discriminates molecular subtypes and has prognostic impact in diffuse large B-cell lymphoma

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    Effect of alternative splicing (AS) on diffuse large B-cell lymphoma (DLBCL) pathogenesis and survival has not been systematically addressed. Here, we compared differentially expressed genes and exons in association with survival after chemoimmunotherapy, and between germinal center B-cell like (GCB) and activated B-cell like (ABC) DLBCLs. Genome-wide exon array-based screen was performed from samples of 38 clinically high-risk patients who were treated in a Nordic phase II study with dose-dense chemoimmunotherapy and central nervous system prophylaxis. The exon expression profile separated the patients according to molecular subgroups and survival better than the gene expression profile. Pathway analyses revealed enrichment of AS genes in inflammation and adhesion-related processes, and in signal transduction, such as phosphatidylinositol signaling system and adenosine triphosphate binding cassette transporters. Altogether, 49% of AS-related exons were protein coding, and domain prediction showed 28% of such exons to include a functional domain, such as transmembrane helix domain or phosphorylation sites. Validation in an independent cohort of 92 DLBCL samples subjected to RNA-sequencing confirmed differential exon usage of selected genes and association of AS with molecular subtypes and survival. The results indicate that AS events are able to discriminate GCB and ABC DLBCLs and have prognostic impact in DLBCL.Peer reviewe

    Loss of chromosome 11q21–23.1 and 17p and gain of chromosome 6p are independent prognostic indicators in B-cell non-Hodgkin's lymphoma

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    Comparative genomic hybridization (CGH) was employed to study chromosomal aberrations in relation to cell proliferation, apoptosis, and patient survival in 94 cases of B-cell non-Hodgkin's lymphoma diagnosed between 1983 and 1993. Eighty cases had aberrations by CGH. Chromosomal regions 1p21–31.1 (10%), 6cen-q24 (12%), 8p (11%), 9p21-ter (14%), 11q21–23.1 (11%), 13q13–21.1 (12%), and 17p (15%) were frequently lost. Gains were found at 3q21-ter (22%), 6p (11%), 7p (12%), 8q23-ter (13%), 12cen-q15 (17%), 17q24-ter (13%), and 18q13.3–21 (20%). A high number of aberrations (≥ 4, 33 cases) was associated (P ≤ 0.001) with the mantle cell and diffuse large B-cell lymphoma subtypes, a high fraction of tumour cells in S phase, and short survival (RR (relative risk) = 3.7). Loss of 1p21–31.1, 8p, 9p21-ter, 11q21–23.1, and 13q13–21.1 were associated with mantle cell lymphoma (P ≤ 0.03), while gain of 6p and 12cen-q15 were more frequent in diffuse large B-cell and small lymphocytic lymphoma, respectively (P = 0.04). Loss of 8p and 17p, and gain of 3q21-ter, 6p, 7p, and 8q23-ter were associated with a high S phase fraction (P ≤ 0.03), but none of the aberrations were associated with tumour apoptotic fraction (P ≥ 0.13). The most important prognostic CGH parameters (P < 0.001) were losses of 11q21–23.1 (RR = 3.8) and 17p (RR = 4.4), and gain of 6p (RR = 4.2). The latter parameters and IPI were the only ones with independent prognostic value (RR = 10, 5.0, 6.7, and 3.7, respectively; P < 0.001) when assessed together with lymphoma sub-type, primary versus relapse cases, treatment, B symptoms, S phase fraction, and presence of BCL1 and BCL2 translocations. A combined CGH/IPI binary parameter had high prognostic value for patients receiving different treatments, with various lymphoma sub-types, and for primary as well as relapse cases.© 2001 Cancer Research Campaign http://www.bjcancer.co
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