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Search Results: 1 - 10 of 127858 matches for " Cauê T. Lopes "
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Evaluation of three methods for sampling ground-dwelling Ants in the Brazilian Cerrado
Lopes, Cauê T.;Vasconcelos, Heraldo L.;
Neotropical Entomology , 2008, DOI: 10.1590/S1519-566X2008000400007
Abstract: few studies have evaluated the efficiency of methods for sampling ants, especially in regions with highly variable vegetation physiognomies such as the cerrado region of central brazil. here we compared three methods to collect ground-dwelling ants: pitfall traps, sardine baits, and the winkler litter extractor. our aim was to determine which method would be most appropriate to characterize the ant assemblages inhabiting different vegetation types. more species were collected with pitfall traps and with the winkler extractor than with sardine baits. pitfall traps collected more species in the cerrado (savanna) physiognomies, particularly in those with a poor litter cover, whereas the winlker extractor was more efficient in the forest physiognomies, except the one subject to periodic inundations. there was a low similarity in species composition between forest and cerrado physiognomies, and this pattern was detected regardless of the method used to sampling ants. therefore, even the use of a single, relatively selective method of collection can be enough for studies comparing highly distinct habitats and/or conditions. however, if the purpose of the sampling is to produce a more thoroughly inventory of the ant fauna, we suggest the use of a combination of methods, particularly pitfall traps and the winkler extractor. therefore, the ants of the leaf-litter (all) sampling protocol appear to be an adequate protocol for sampling ants in the highly-threatened brazilian cerrado biome.
Estratifica??o vertical de formigas em cerrado strictu sensu no Parque Estadual da Serra de Caldas Novas, Goiás, Brasil
Campos, Ricardo I.;Lopes, Cauê T.;Magalh?es, Wagner C. S.;Vasconcelos, Heraldo L.;
Iheringia. Série Zoologia , 2008, DOI: 10.1590/S0073-47212008000300004
Abstract: formicidae is an abundant group in the soil and is also well distributed in all vegetation strata, representing a good model for studies on vertical stratification of the fauna. the aim of this study was to verify a possible stratification of ant assemblages inhabiting the soil, the lower and the higher vegetation strata. data was collected in the serra de caldas novas state park, in an area of cerrado strictu sensu. ant collection was performed using pitfall traps. a total of 11 traps were placed in the soil, 17 in the lower vegetation stratum (dominated by shrubs and small trees) and 23 in the higher vegetation stratum (dominated by taller, mature trees). forty-nine species of ants from 15 genera and five subfamilies were collected. accumulation curves indicated that there is 37.5% more species in the soil than in mature trees and 35% more species in mature trees than in shrubs/young trees. there was not a clear vertical stratification between the soil and the two vegetation strata. therefore, the species present in the vegetation tended to represent a nested subset of those found in the soil. even without a clear vertical stratification, the diversity of ants in the cerrado vegetation is high, and part of this diversity appears to be explained by the fact that some species are specialized in nesting and/or foraging in the soil, while others in the vegetation.
Dynamics of the Leaf-Litter Arthropod Fauna Following Fire in a Neotropical Woodland Savanna
Heraldo L. Vasconcelos,Renata Pacheco,Raphael C. Silva,Pedro B. Vasconcelos,Cauê T. Lopes,Alan N. Costa,Emilio M. Bruna
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0007762
Abstract: Fire is an important agent of disturbance in tropical savannas, but relatively few studies have analyzed how soil-and-litter dwelling arthropods respond to fire disturbance despite the critical role these organisms play in nutrient cycling and other biogeochemical processes. Following the incursion of a fire into a woodland savanna ecological reserve in Central Brazil, we monitored the dynamics of litter-arthropod populations for nearly two years in one burned and one unburned area of the reserve. We also performed a reciprocal transplant experiment to determine the effects of fire and litter type on the dynamics of litter colonization by arthropods. Overall arthropod abundance, the abundance of individual taxa, the richness of taxonomic groups, and the species richness of individual taxa (Formiciade) were lower in the burned site. However, both the ordinal-level composition of the litter arthropod fauna and the species-level composition of the litter ant fauna were not dramatically different in the burned and unburned sites. There is evidence that seasonality of rainfall interacts with fire, as differences in arthropod abundance and diversity were more pronounced in the dry than in the wet season. For many taxa the differences in abundance between burned and unburned sites were maintained even when controlling for litter availability and quality. In contrast, differences in abundance for Collembola, Formicidae, and Thysanoptera were only detected in the unmanipulated samples, which had a lower amount of litter in the burned than in the unburned site throughout most of our study period. Together these results suggest that arthropod density declines in fire-disturbed areas as a result of direct mortality, diminished resources (i.e., reduced litter cover) and less favorable microclimate (i.e., increased litter desiccation due to reduction in tree cover). Although these effects were transitory, there is evidence that the increasingly prevalent fire return interval of only 1–2 years may jeopardize the long-term conservation of litter arthropod communities.
Cyatta abscondita: Taxonomy, Evolution, and Natural History of a New Fungus-Farming Ant Genus from Brazil
Jeffrey Sosa-Calvo, Ted R. Schultz, Carlos R. F. Brand?o, Christiana Klingenberg, Rodrigo M. Feitosa, Christian Rabeling, Maurício Bacci, Cauê T. Lopes, Heraldo L. Vasconcelos
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0080498
Abstract: Cyatta abscondita, a new genus and species of fungus-farming ant from Brazil, is described based on morphological study of more than 20 workers, two dealate gynes, one male, and two larvae. Ecological field data are summarized, including natural history, nest architecture, and foraging behavior. Phylogenetic analyses of DNA sequence data from four nuclear genes indicate that Cyatta abscondita is the distant sister taxon of the genus Kalathomyrmex, and that together they comprise the sister group of the remaining neoattine ants, an informal clade that includes the conspicuous and well-known leaf-cutter ants. Morphologically, Cyatta abscondita shares very few obvious character states with Kalathomyrmex. It does, however, possess a number of striking morphological features unique within the fungus-farming tribe Attini. It also shares morphological character states with taxa that span the ancestral node of the Attini. The morphology, behavior, and other biological characters of Cyatta abscondita are potentially informative about plesiomorphic character states within the fungus-farming ants and about the early evolution of ant agriculture.
Immunoreactivity of thymosin beta 4 in human foetal and adult genitourinary tract
S. Nemolato,T. Cabras,M.U. Fanari,F. Cau
European Journal of Histochemistry , 2010, DOI: 10.4081/ejh.2010.e43
Abstract: Thymosins beta 4 (Tβ4) is a member of the beta-thymosins family, a family of peptides playing essential roles in many cellular functions. Our recent studies suggested Tβ4 plays a key role in the development of human salivary glands and the gastrointestinal tract. The aim of this study was to analyse the presence of Tβ4 in the human adult and foetal genitourinary tract. Immunolocalization of Tβ4 was studied in autoptic samples of kidney, bladder, uterus, ovary, testicle and prostate obtained from four human foetuses and four adults. Presence of the peptide was observed in cells of different origin: in surface epithelium, in gland epithelial cells and in the interstitial cells. Tβ4 was mainly found in adult and foetal bladder in the transitional epithelial cells; in the adult endometrium, glands and stromal cells were immunoreactive for the peptide; Tβ4 was mainly localized in the glands of foetal prostate while, in the adults a weak Tβ4 reactivity was restricted to the stroma. In adult and foetal kidney, Tβ4 reactivity was restricted to ducts and tubules with completely spared glomeruli; a weak positivity was observed in adult and foetal oocytes; immunoreactivity was mainly localized in the interstitial cells of foetal and adult testis. In this study, we confirm that Tβ4 could play a relevant role during human development, even in the genitourinary tract, and reveal that immunoreactivity for this peptide may change during postnatal and adult life.
Expression pattern of thymosin beta 4 in the adult human liver
S. Nemolato,P. Van Eyken,T. Cabras,F. Cau
European Journal of Histochemistry , 2011, DOI: 10.4081/ejh.2011.e25
Abstract: Thymosin beta-4 (Tβ4) is a member of beta-thymosins, a family of small peptides involved in polymerization of G-actin, and in many critical biological processes including apoptosis, cell migration, angiogenesis, and fibrosis. Previous studies in the newborn liver did not reveal any significant reactivity for Tβ4 during the intrauterine life. The aim of the present study was to investigate by immunohistochemistry Tβ4 expression in the adult normal liver. Thirty-five human liver samples, including 11 needle liver biopsies and 24 liver specimens obtained at autopsy, in which no pathological change was detected at the histological examination, were immunostained utilizing an anti-Tβ4 commercial antibody. Tβ4 was detected in the hepatocytes of all adult normal livers examined. A zonation of Tβ4 expression was evident in the vast majority of cases. Immunostaining was preferentially detected in zone 3, while a minor degree of reactivity was detected in periportal hepatocytes (zone 1). At higher power, Tβ4-reactive granules appeared mainly localized at the biliary pole of hepatocytes. In cases with a strong immunostaining, even perinuclear areas and the sinusoidal pole of hepatocytes appeared interested by immunoreactivity for Tβ4. The current work first evidences a strong diffuse expression of Tβ4 in the adult human liver, and adds hepatocytes to the list of human cells able to synthesize large amounts of Tβ4 in adulthood. Moreover, Tβ4 should be added to the liver proteins characterized by a zonate expression pattern, in a descending gradient from the terminal vein to the periportal areas of the liver acinus. Identifying the intimate role played by this peptide intracellularly and extracellularly, in physiology and in different liver diseases, is a major challenge for future research focusing on Tβ4.
Thymosin beta 4 expression in normal skin, colon mucosa and in tumor infiltrating mast cells
S. Nemolato,T. Cabras,M.U. Fanari,F. Cau
European Journal of Histochemistry , 2010, DOI: 10.4081/ejh.2010.e3
Abstract: Mast cells (MCs) are metachromatic cells that originate from multipotential hemopoietic stem cells in the bone marrow. Two distinct populations of MCs have been characterized: mucosal MCs are tryptase-positive while mast cells in skin contain tryptase and chymase. We now show that a sub-population of MCs is highly immunoreactive for thymosin β4, as revealed by immunohistochemical analyses of normal skin, normal colon mucosa and salivary gland tumors. Four consecutive serial sections from each case were immunostained for thymosin β4 (Tβ4), chymase, tryptase and stained for toluidine blue. In skin biopsies, MCs showed a comparable immunoreactivity for Tβ4, chymase and tryptase. In normal colon mucosa the vast majority of mucosal MCs expressed a strong cytoplasmic immunoreactivity for tryptase and for Tβ4, in the absence of chymase reactivity. A robust expression of Tβ4 was detected in tumor-infiltrating and peritumoral mast cells in salivary gland tumors and breast ductal infiltrating carcinomas. Tumor-infiltrating MCs also showed a strong immunoreactivity for chymase and tryptase. In this paper, we first demonstrate that normal dermal and mucosal mast cells exhibit strong expression of thymosin β4, which could be considered a new marker for the identification of mast cells in skin biopsies as well as in human tumors. The possible relationship between the degree of Tβ4 expression in tumor-infiltrating mast cells and tumor behaviour warrants further consideration in future investigations.
“Quanto più mi avvicino alla parola, più essa sanguina.” Karl Kraus e la lingua in rivolta
Maurizio Cau
lo Squaderno , 2009,
Abstract: Non capita di frequente che affilati progetti di rivolta vengano condotti con l’obiettivo di ripristinare un preciso ordine legale, specie se l’ordinamento di cui si invoca la salvaguardia ha contorni squisitamente linguistici. Un simile disegno ha guidato per trentasette anni la mano di Karl Kraus (1874-1936), impegnato in una lotta senza quartiere contro le debolezze della frase fatta e l’incultura di una civiltà pronta a sostituire la piattezza dell’ opinione alla profondità del pensiero .
La via maestra alla giustizia sociale. Alcide De Gasperi tra solidarismo e corporativismo
Maurizio Cau
Scienza & Politica : per una Storia delle Dottrine , 2009, DOI: 10.6092/issn.1825-9618/2738
Abstract: La via maestra alla giustizia sociale. Alcide De Gasperi tra solidarismo e corporativismo
Notch activity in the nervous system: to switch or not switch?
Elise Cau, Patrick Blader
Neural Development , 2009, DOI: 10.1186/1749-8104-4-36
Abstract: The Notch pathway is a crucial signalling pathway involved in development and disease that functions through the binding of transmembrane ligands (the DSL proteins, for Delta-Serrate-Lag2) to transmembrane receptors (the Notch molecules) on adjacent cells. Such binding triggers the proteolysis of Notch and the release of its intracellular domain (the so-called Notch-intra fragment), which is translocated into the nucleus. Canonical Notch signalling involves the binding of Notch-intra to DNA-binding cofactors belonging to the CSL family (for CBF1 in human, Suppressor of Hairless in Drosophila and Lag-1 in Caenorhabditis elegans) [1,2]. Notch-intra/CSL complexes subsequently activate transcription of target genes through the recruitment of the histone-acetyl transferases CBP/p300 [3,4] and PCAF [5].Notch activity has been extensively studied in the Drosophila nervous system, where it regulates cell fate choice in several different contexts. First, the Notch pathway is required to select single cells to become neural precursors from a cluster of equipotent progenitors that express basic helix-loop-helix (bHLH) transcription factors called proneural genes (Figure 1A). Expression of proneural genes endows cells with a neural potential as these genes are both necessary and sufficient for the formation of neural progenitors [6]. In situations where Notch activity is absent, all the cells from the clusters retain expression of the proneural genes and become neural cells [7-11]. Conversely, when Notch signalling is activated constitutively, all the cells of the cluster acquire an epidermal fate [12-14]. These observations led to the following model whereby cells within proneural clusters communicate via an inhibitory feed-back loop of Notch activity. After several iterations of the loop, only one cell of the cluster downregulates the Notch pathway, retains proneural expression and becomes a neural precursor. The remaining cells, which still have the neural fate inhibited by
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