952 resultados para larval description
Resumo:
Natural anti-parasitic compounds in plants such as condensed tannins (CT) have anthelmintic properties against a range of gastrointestinal nematodes, but for other helminths such effects are unexplored. The aim of this study was to assess the effects of CT from three different plant extracts in a model system employing the rat tapeworm, Hymenolepis diminuta, in its intermediate host, Tenebrio molitor. An in vitro study examined infectivity of H. diminuta cysticercoids (excystation success) isolated from infected beetles exposed to different concentrations of CT extracts from pine bark (PB) (Pinus sps), hazelnut pericarp (HN) (Corylus avellana) or white clover flowers (WC) (Trifolium repens), in comparison with the anthelmintic drug praziquantel (positive control). In the in vitro study, praziquantel and CT from all three plant extracts had dose-dependent inhibitory effects on cysticercoid excystation. The HN extract was most effective at inhibiting excystation, followed by PB and WC. An in vivo study was carried out on infected beetles (measured as cysticercoid establishment) fed different doses of PB, HN and praziquantel. There was a highly significant inhibitory effect of HN on cysticercoid development (p = 0.0002). Overall, CT showed a promising anti-cestodal effect against the metacestode stage of H. diminuta.
Resumo:
This paper proposes a limitation to epistemological claims to theory building prevalent in critical realist research. While accepting the basic ontological and epistemological positions of the perspective as developed by Roy Bhaskar, it is argued that application in social science has relied on sociological concepts to explain the underlying generative mechanisms, and that in many cases this has been subject to the effects of an anthropocentric constraint. A novel contribution to critical realist research comes from the work and ideas of Gregory Bateson. This is in service of two central goals of critical realism, namely an abductive route to theory building and a commitment to interdisciplinarity. Five aspects of Bateson’s epistemology are introduced: (1) difference, (2) logical levels of abstraction, (3) recursive causal loops, (4) the logic of metaphor, and (5) Bateson’s theory of mind. The comparison between Bateson and Bhaskar’s ideas is seen as a form of double description, illustrative of the point being raised. The paper concludes with an appeal to critical realists to start exploring the writing and outlook of Bateson himself.
Resumo:
Ants often form mutualistic interactions with aphids, soliciting honeydew in return for protective services. Under certain circumstances, however, ants will prey upon aphids. In addition, in the presence of ants aphids may increase the quantity or quality of honeydew produced, which is costly. Through these mechanisms, ant attendance can reduce aphid colony growth rates. However, it is unknown whether demand from within the ant colony can affect the ant-aphid interaction. In a factorial experiment, we tested whether the presence of larvae in Lasius niger ant colonies affected the growth rate of Aphis fabae colonies. Other explanatory variables tested were the origin of ant colonies (two separate colonies were used) and previous diet (sugar only or sugar and protein). We found that the presence of larvae in the ant colony significantly reduced the growth rate of aphid colonies. Previous diet and colony origin did not affect aphid colony growth rates. Our results suggest that ant colonies balance the flow of two separate resources from aphid colonies- renewable sugars or a protein-rich meal, depending on demand from ant larvae within the nest. Aphid payoffs from the ant-aphid interaction may change on a seasonal basis, as the demand from larvae within the ant colony waxes and wanes.
Resumo:
The general circulation models used to simulate global climate typically feature resolution too coarse to reproduce many smaller-scale processes, which are crucial to determining the regional responses to climate change. A novel approach to downscale climate change scenarios is presented which includes the interactions between the North Atlantic Ocean and the European shelves as well as their impact on the North Atlantic and European climate. The goal of this paper is to introduce the global ocean-regional atmosphere coupling concept and to show the potential benefits of this model system to simulate present-day climate. A global ocean-sea ice-marine biogeochemistry model (MPIOM/HAMOCC) with regionally high horizontal resolution is coupled to an atmospheric regional model (REMO) and global terrestrial hydrology model (HD) via the OASIS coupler. Moreover, results obtained with ROM using NCEP/NCAR reanalysis and ECHAM5/MPIOM CMIP3 historical simulations as boundary conditions are presented and discussed for the North Atlantic and North European region. The validation of all the model components, i.e., ocean, atmosphere, terrestrial hydrology, and ocean biogeochemistry is performed and discussed. The careful and detailed validation of ROM provides evidence that the proposed model system improves the simulation of many aspects of the regional climate, remarkably the ocean, even though some biases persist in other model components, thus leaving potential for future improvement. We conclude that ROM is a powerful tool to estimate possible impacts of climate change on the regional scale.
Resumo:
This paper describes the development and basic evaluation of decadal predictions produced using the HiGEM coupled climate model. HiGEM is a higher resolution version of the HadGEM1 Met Office Unified Model. The horizontal resolution in HiGEM has been increased to 1.25◦ × 0.83◦ in longitude and latitude for the atmosphere, and 1/3◦ × 1/3◦ globally for the ocean. The HiGEM decadal predictions are initialised using an anomaly assimilation scheme that relaxes anomalies of ocean temperature and salinity to observed anomalies. 10 year hindcasts are produced for 10 start dates (1960, 1965,..., 2000, 2005). To determine the relative contributions to prediction skill from initial conditions and external forcing, the HiGEM decadal predictions are compared to uninitialised HiGEM transient experiments. The HiGEM decadal predictions have substantial skill for predictions of annual mean surface air temperature and 100 m upper ocean temperature. For lead times up to 10 years, anomaly correlations (ACC) over large areas of the North Atlantic Ocean, the Western Pacific Ocean and the Indian Ocean exceed values of 0.6. Initialisation of the HiGEM decadal predictions significantly increases skill over regions of the Atlantic Ocean,the Maritime Continent and regions of the subtropical North and South Pacific Ocean. In particular, HiGEM produces skillful predictions of the North Atlantic subpolar gyre for up to 4 years lead time (with ACC > 0.7), which are significantly larger than the uninitialised HiGEM transient experiments.
Resumo:
P>Nongeniculate Corallinaceae are poorly known in Brazil. In our endeavor to identify this group of seaweeds along the Brazilian coast we came across some specimens that fit well into the accepted circumscription of Litothamnion Heydrich. Within this genus they could be identified to what has been called L. superpositum Foslie. The specimens were represented by nongeniculate, free living specimens (rhodoliths); lumpy to fruticose growth-form, presenting flared epithallial cells in transversal section; multiporate tetrasporangial conceptacles, with roof protruding above or flush with the surrounding thallus surface; chambers 250-525 mu m in diameter and 150-230 mu m high, roof structured by filaments with 3-5 cells long; and pores in depression. Among the species described from the Brazilian coast, L. heteromorphum (Foslie) Foslie presented anatomical and reproductive characteristics similar to the referred species described from southern Africa and Australia. Therefore, we propose to consider L. heteromorphum as a heterotypic synonym of L. superpositum and extending its distribution to the Western Atlantic.
Resumo:
Mitotic chromosomes of Metynnis maculatus (KNER 1860) (Teleostei, Characiformes), a fish species that occurs in the Amazon and Parana-Paraguay river basins, were analyzed for the first time by Giemsa and Ag-NOR staining, C-banding and fluorescence in situ hybridization (FISH) with 18S and 5S rDNA sequences. The basic chromosome number of the species is 2n=62 (32M+22SM+4ST+4A) and, in addition to the 62 regular chromosomes, one small acrocentric supernumerary B chromosome was found in part of the specimens analyzed. Four active NORs were present, and constitutive heterochromatin blocks were found in the pericentromeric region of several chromosomes. A heterochromatic block was also present in the interstitial portion of the submetacentric NOR-bearing pair and the B chromosome was entirely heterochromatic. FISH using an 18S rDNA probe confirmed the results obtained with AgNO(3) staining, and an additional signal was also present on the B chromosomes. 5S rDNA sequences mapped only to the largest acrocentric pair. This is the first description of supernumerary B chromosomes in Serrasalminae, and this karyotype characterization may be useful in further studies about chromosome evolution in this fish group.
Resumo:
In studies carried out off the north-eastern and south-eastern coast of Brazil, three species of Prosphaerosyllis were found: P. isabellae, which was already recorded for Brazilian waters; P. xarifae, a newly recorded species for the area; and P. brachycephala sp. nov., a new to science species. Prosphaerosyllis brachycephala sp. nov., is characterized by having swollen anterior part of the body, prostomium retractable within the peristomium and anterior segments, short antennae, short peristomial and dorsal cirri, and falcigers with short, unidentate blades throughout. All these species are herein described and compared to the most similar congeners.
Resumo:
A new species of Stygnidae is described from the state of Bahia, Brazil. Protimesius bahiensis sp. nov. can be distinguished from the remaining species of the genus by the combination of: male femur IV unarmed and cylindrical; male patella IV with a row of large dorsal acute tubercles, increasing in size distally and male tibia IV with one mesodistal tubercle; ventral plate of the penis with three pairs of distal curved setae and one pair of intermediate setae, smaller than the rest. A cladistic analysis of the subfamily is presented. Stygninae is divided in two groups of genera: (Ricstygnus, Stygnus, Sickesia), with a wide distribution and (Pickeliana (Protimesius (Phareus (Stenophareus (Auranus (Verrucastygnus, Stenostygnoides)))))), associated to the Guiana Shield, Amazon basin and Northeastern Brazil. The monophyly of Protimesius is supported by the apex of pedipalpal tibia sockets bifid (homoplastically present in Verrucastygnus and Stenostygnoides) and by the presence of scopulae with non-spatulated hairs.
Resumo:
Surazomus uarini n. sp. is described and illustrated based on specimens collected by beating on understory vegetation of Amazonian ""terra firme"" upland rain forests. A new cuticular structure, possibly a gland opening, is described on the female tarsus I and terminal flagellum. A putatively homologous structure is reported from the same body parts in all Undescribed species of Rowlandius Reddell and Cokendolpher 1995; Stenochrus portoricensis Chamberlin 1922; Mastigoproctus maximus (Tarnani 1889), and Thelyphonellus amazonicus (Butler 1872); suggesting it new synapomorphy for the clade Uropygi (i.e., Schizomida + Thelyphonida).
Resumo:
Of the three superfamilies of Ostracoda present in fresh water, only the Cytheroidea had thus far no records in terrestrial environments. Here, we report on a new genus and species, Intrepidocythere ibipora n. gen. n. sp., of the ostracod superfamily Cytheroidea, from forest leaf litter in Sao Paulo State, Brazil. Judging from morphological similarities, this new genus is believed to be closely related to the genus Elpidium. Possible pathways that led to the colonisation of terrestrial habitats are discussed, and an overview is given on the distribution of the known terrestrial ostracod lineages. The present findings strengthen the idea that terrestrial ostracods are more common than previously thought, at least in tropical areas.
Resumo:
Protimesius osvaldoi sp. nov. is described from the Reserva Biologica de Sooretama, state of Espirito Santo, Southeastern Brazil, being the First record of Stygnidae from this State and the southernmost record of the family in the Brazilian Atlantic Forest (hitherto, the family was recorded down to Bahia only), extending in 210 km south of the previously known distribution. This is a large species, with armature of leg IV very reduced and penial morphology differing from the closest counterparts mainly in the ventral plate, which recedes deeply at the lateral borders and has the distal margin curved ventrally and by the presence of two small intermediate setae. Protimesius Roewer, 1913 consisted hitherto of 17 species, recorded from northern/northeastern Brazil and Amazonia of adjacent Countries. A key is given for the 17 species of Protimesius for which males are known.
Resumo:
A cladistic analysis was applied to test the monophyly of the genus Isoctenus. The data matrix comprised 28 taxa scored for 53 morphological and two behavioural characters. The analysis resulted in two equally parsimonious trees of 89 steps. The strict consensus was used to discuss the relationships of Isoctenus and related Cteninae genera. Ctenopsis Schmidt is synonymized with Isoctenus. Isoctenus foliifer Bertkau, I. strandi Mello-Leitao, I. eupalaestrus Mello-Leitao, I. janeirus (Walckenaer), I. coxalis (Pickard-Cambridge), I. corymbus Polotow, Brescovit & Pellegatti-Franco and I. malabaris Polotow, Brescovit & Ott are maintained in Isoctenus. Four species currently included in Ctenus are transferred to Isoctenus: I. griseolus (Mello-Leitao) comb. nov., I. taperae (Mello-Leitao) comb. nov., I. herteli (Mello-Leitao) comb. nov. and I. minusculus (Keyserling) comb. nov. The following specific names are synonymized: Ctenus sanguineus Walckenaer, C. semiornatus Mello-Leitao and Ctenopsis stellata Schmidt with Isoctenus janeirus (Walckenaer), Ctenus mourei Mello-Leitao with Isoctenus herteli (Mello-Leitao) and Ctenus pauper Mello-Leitao with Isoctenus strandi Mello-Leitao. Isoctenus sigma Schenkel, described from French Guiana, is transferred to Ctenus. Four species are newly described: Isoctenus areia sp. nov. from Paraiba, Brazil, I. charada sp. nov. and I. segredo sp. nov. from Parana, Brazil, and I. ordinario sp. nov. from south and south-eastern Brazil and north-eastern Argentina. Isoctenus latevittatus Caporiacco is considered species inquirenda. Parabatinga gen. nov. is proposed to include Ctenus brevipes Keyserling. The following synonymies are established: Ctenus taeniatus Keyserling, C. tatarandensis Tullgren, C. anisitsi Strand, C. atrivulvus Strand, C. mentor Strand, C. brevipes brevilabris Strand, Isoctenus masculus Mello-Leitao and Ctenus birabeni Mello-Leitao with Parabatinga brevipes (Keyserling) comb. nov. (C) 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155, 583-614.