Trypanosoma cruzi trypomastigotes induce cytoskeleton modifications during HeLa cell invasion

It has been recently shown that Trypanosoma cruzi trypomastigotes subvert a constitutive membrane repair mechanism to invade HeLa cells. Using a membrane extraction protocol and high-resolution microscopy, the HeLa cytoskeleton and T. cruzi parasites were imaged during the invasion process after 15 min and 45 min. Parasites were initially found under cells and were later observed in the cytoplasm. At later stages, parasite-driven protrusions with parallel filaments were observed, with trypomastigotes at their tips. We conclude that T. cruzi trypomastigotes induce deformations of the cortical actin cytoskeleton shortly after invasion, leading to the formation of pseudopod-like structures.

Molecular and morphological characterization of hydrochar produced by microwave-assisted hydrothermal carbonization of cellulose

The objective of this work was to characterize the morphology and molecular composition of the hydrochar produced by microwave-assisted hydrothermal carbonization of cellulose. The produced hydrochar consists mainly of aggregate microspheres with about 2.0 µm in diameter, with aliphatic and aromatic structures and the presence of carbonyl functional groups. The aromatic groups are formed mainly by benzofuran-like structures, being chemically different from common cellulose char. Microwave-assisted hydrothermal carbonization yields a functionalized carbon-rich material similar to that produced by the conventional hydrothermal process.

Dissulfeto de molibdênio, um material multifuncional e surpreendente

The aim of this work is to review the chemical and physical properties of layered molybdenum disulfide. The three polymorphic/polytypic modifications of the compound were found, the polytypes 2H (molybdenite) and 3R are semiconductors while the polymorph 1T is an electronic conductor. 2H-MoS2 has several important industrial applications as hydrotreatment catalysts, energy storage devices, solar cells, solid lubricants, among others. When intercalated, the 2H phase changes to a distorted 1T phase, producing unstable intercalation compounds that can be exfoliated in solution, producing single layers and consequently nanocomposites. The direct synthesis of the 1T phase produces stable intercalation compounds. Recently molybdenum disulfide was prepared as nanotubes and fulerene-like structures that bring new insights in the investigation of this important material.

Histopathological and immunohistochemical findings of swine with spontaneous influenza A infection in Brazil, 2009-2010

Swine influenza (SI) is caused by the type A swine influenza virus (SIV). It is a highly contagious disease with a rapid course and recovery. The major clinical signs and symptoms are cough, fever, anorexia and poor performance. The disease has been associated with other co-infections in many countries, but not in Brazil, where, however, the first outbreak has been reported in 2011. The main aim of this study was to characterize the histological features in association with the immunohistochemical (IHC) results for influenza A (IA), porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) in lung samples from 60 pigs submitted to Setor de Patologia Veterinária at the Universidade Federal do Rio Grande do Sul (SPV-UFRGS), Brazil, during 2009-2010. All of these lung samples had changes characterized by interstitial pneumonia with necrotizing bronchiolitis, never observed previously in the evaluation of swine lungs in our laboratory routine. Pigs in this study had showed clinical signs of a respiratory infection. Swine samples originated from Rio Grande do Sul 31 (52%), Santa Catarina 14 (23%), Paraná 11 (18%), and Mato Grosso do Sul 4 (7%). Positive anti-IA IHC labelling was observed in 45% of the cases, which were associated with necrotizing bronchiolitis, atelectasis, purulent bronchopneumonia and hyperemia. Moreover, type II pneumocyte hyperplasia, alveolar and bronchiolar polyp-like structures, bronchus-associated lymphoid tissue (BALT) hyperplasia and pleuritis were the significant features in negative anti-IA IHC, which were also associated with chronic lesions. There were only two cases with positive anti-PCV2 IHC and none to PRRSV. Therefore, SIV was the predominant infectious agent in the lung samples studied. The viral antigen is often absent due to the rapid progress of SI, which may explain the negative IHC results for IA (55%); therefore, IHC should be performed at the beginning of the disease. This study has shown how important a careful histological evaluation is for the diagnosis. Since 2009, a new histological feature of swine pneumonia in animals with respiratory clinical signs has been observed in samples from pigs with clinical respiratory disease submitted to SPV-UFRGS. In addition, the results proved the importance of histological evaluation for swine herd health management.

Histological changes in banana explants, cv. Nanicão (Musa spp., Group AAA), submitted to different auxins for induction of somatic embryogenesis

The present work analyzes the behavior of banana explants, cv. Nanicão (Musa spp. Group AAA) regarding somatic embryogenesis induction treatments with several auxins. Longitudinal segments of shoot meristematic apices of micropropagated banana plantlets cultivated and rooted in vitro were introduced in culture medium containing dicamba, picloram, 2,4-D or NAA in different concentrations. Explant samples were collected at 0, 7 and 10 days and prepared for light microscopy. Histological sections were used for comparison of the histological changes occurring after induction treatment with different auxins. Embryogenic response was observed only in treatments with picloram or dicamba, with distinct embryogenic regions observed at 14 and 21 days in culture, respectively. Histological sections of embryogenic regions of the explant at 26 days in culture revealed the formation of meristematic regions, structures with multiple root meristems, and somatic embryos at early globular stages. Embryo-like structures morphologically similar to Musa balbisiana zygotic embryos were sectioned and showed a lack of apical meristems and absence of procambial differentiation. These results indicate the induction of non-functional somatic embryos and the need for more studies on developmental aspects and maturation treatments for optimization of the process.

Oil glands in the Neotropical genus Dahlstedtia Malme (Leguminosae, Papilionoideae, Millettieae)

Dahlstedtia pentaphylla (Taub.) Burkart and D. pinnata (Benth.) Malme belong to the Millettieae tribe and are tropical leguminous trees that produce a strong and unpleasant odour. In the present work, we investigated the distribution, development and histochemistry of foliar and floral secretory cavities that could potentially be related to this odour. The ultrastructure of foliar secretory cavities were also studied and compared with histochemical data. These data were compared with observations recorded for other species of Millettieae in order to gain a phylogenetic and taxonomic perspective. Foliar secretory cavities were only recorded for D. pentaphylla. Floral secretory cavities were present in the calyx, wings and keels in both species; in D. pinnata they also were found in bracteoles and vexillum. Such structures were found to originate through a schizogenous process. Epithelial cells revealed a large amount of flattened smooth endoplasmic reticula, well-developed dictyosomes and vacuoles containing myelin-like structures. Cavity lumen secretion stains strongly for lipids. Features of the secretory cavities studied through ultrastructural and histochemical procedures identify these structures as oil glands. Thus, if the odour produced by such plants has any connection with the accumulation of rotenone, as other species belonging to the "timbó" complex, the lipophilic contents of the secretory cavities of Dahlstedtia species take no part in such odour production. The presence, distribution patterns and frequencies of secretory structures in Dahlstedtia are taxonomically significant and may be utilized as a diagnostic character which justifies the separation of this genus into two species.

Gap junctions in cells of the immune system: structure, regulation and possible functional roles

Gap junction channels are sites of cytoplasmic communication between contacting cells. In vertebrates, they consist of protein subunits denoted connexins (Cxs) which are encoded by a gene family. According to their Cx composition, gap junction channels show different gating and permeability properties that define which ions and small molecules permeate them. Differences in Cx primary sequences suggest that channels composed of different Cxs are regulated differentially by intracellular pathways under specific physiological conditions. Functional roles of gap junction channels could be defined by the relative importance of permeant substances, resulting in coordination of electrical and/or metabolic cellular responses. Cells of the native and specific immune systems establish transient homo- and heterocellular contacts at various steps of the immune response. Morphological and functional studies reported during the last three decades have revealed that many intercellular contacts between cells in the immune response present gap junctions or "gap junction-like" structures. Partial characterization of the molecular composition of some of these plasma membrane structures and regulatory mechanisms that control them have been published recently. Studies designed to elucidate their physiological roles suggest that they might permit coordination of cellular events which favor the effective and timely response of the immune system.

Cultivation and identification of colon cancer stem cell-derived spheres from the Colo205 cell line

Our group established a method to culture spheres under serum-free culture condition. However, the biological characteristics and the tumorigenicity of spheres are unknown. Here, we demonstrate that sphere cells expressed high levels of the putative colorectal cancer stem cell markers CD133 and CD44. The CD133-positive rates were 13.27 ± 5.62, 52.71 ± 16.97 and 16.47 ± 2.45% in sphere cells, regular Colo205 cells and differentiated sphere cells, respectively, while the CD44-positive rates were 62.92 ± 8.38, 79.06 ± 12.10 and 47.80 ± 2.5%, respectively, and the CD133/CD44-double-positive rates were 10.77 ± 4.96, 46.89 ± 19.17 and 12.41 ± 2.27%, respectively (P < 0.05). Cancer sphere cells formed crypt-like structures in 3-D culture. Moreover, cells from cancer spheres exhibited more tumorigenicity than regular Colo205 cells in a xenograft assay. The cancer sphere cells displayed much higher oncogenicity than regular Colo205 cells to initiate neoplasms, as assayed by H&E staining, Musashi-1 staining and electron microscopy. Our findings indicated that the sphere cells were enriched with cancer stem cells (CSCs), and exhibited more proliferation capacity, more differentiation potential and especially more tumorigenicity than regular Colo205 cells in vitro and in vivo. Further isolation and characterization of these CSCs may provide new insights for novel therapeutic targets and prognostic markers.

Would Sacaca, Croton cajucara Benth (Euphorbiaceae) be an hepatotoxic plant like Germander, Teucrium chamaedrys L. (Labiatae)?

Clinical and experimental studies have consistently incriminated the medicinal plant germander (Teucrium chamaedrys L.) in epidemic and sporadic cases of liver diseases. The sacaca (Croton cajucara Benth), a common plant in Brazilian Amazon region also comes being incriminated in similar clinical cases. Of both plants were isolated diterpenoid coumpounds with similar chemical structures.

Influence of floral structure and flower bud quality on productivity and fruit shape in different apple cultivars

This study examines the relationship between floral structure and bud quality with the productivity and fruit shape of Gala, Fuji and Daiane apple cultivars under the mild winter conditions in Southern Brazil. Six different types of floral structures were characterized in field growing plants, according to their nature and bud size: spurs, short and long twigs with weak and vigorous buds. Variables related to the phenology and the productivity for these different structures were evaluated. Gala and Fuji cvs. showed earlier phenological development in the twigs, and cv. Daiane in the spurs. For the three cvs. the highest percentage of buds in each phenological phase was observed in the long twigs. The long twigs also showed the highest sprout and fruit set index, floral number per cluster, and leaf area in the three cvs., while the bud abortion was higher in the spurs than in the twigs. No difference was observed among the structures in cvs. Gala and Fuji regarding to the fruit shape. In the cv. Daiane, however, a tendency to higher length diameter ratio of the fruits produced by the long twigs was observed.

Absence-like seizures in adult rats following pilocarpine-induced status epilepticus early in life

Administration of pilocarpine causes epilepsy in rats if status epilepticus (SE) is induced at an early age. To determine in detail the electrophysiological patterns of the epileptogenic activity in these animals, 46 Wistar rats, 7-17 days old, were subjected to SE induced by pilocarpine and electro-oscillograms from the cortex, hippocampus, amygdala, thalamus and hypothalamus, as well as head, rostrum and vibrissa, eye, ear and forelimb movements, were recorded 120 days later. Six control animals of the same age range did not show any signs of epilepsy. In all the rats subjected to SE, iterative spike-wave complexes (8.1 ± 0.5 Hz in frequency, 18.9 ± 9.1 s in duration) were recorded from the frontal cortex during absence fits. However, similar spike-wave discharges were always found also in the hippocampus and, less frequently, in the amygdala and in thalamic nuclei. Repetitive or single spikes were also detected in these same central structures. Clonic movements and single jerks were recorded from all the rats, either concomitantly with or independently of the spike-wave complexes and spikes. We conclude that rats made epileptic with pilocarpine develop absence seizures also occurring during paradoxical sleep, showing the characteristic spike-wave bursts in neocortical areas and also in the hippocampus. This is in contrast to the well-accepted statement that one of the main characteristics of absence-like fits in the rat is that spike-wave discharges are never recorded from the hippocampal fields.

What does the field of International Relations look like in South America?

Abstract This article provides a comprehensive picture of IR in South America by applying content analysis to 7,857 articles published in 35 journals from six South American countries from 2006 to 2014 in order to discover what the predominant theories, methods and research areas in this field are, how scholars tend to combine them in their research designs, and what the profiles of regional journals are, regarding their epistemological, methodological and subject preferences. The findings reveal a predominantly Positivist and largely Qualitative discipline, resembling North American and European IR.

A blockmodel study of managerial hierarchies, verbal networks, and organizational culture in four hospitals

This study demonstrates and applies a social network methodology for studying the dynamics of hierarchies in organizations. Social network (blockmodel) analysis of verbal networks in four hospitals contrasted hierarchical and structurally equivalent partitions of the sociomatrices of frequent ties and perceptions of organizational culture. It was found that the verbal networks in these organizations follow a center periphery pattern rather than a hierarchical logic and that perceptions of culture vary more by verbal network than by formal hierarchy. The perceptions of culture of central groups in one organization are much like those of peripheral groups in another. In all four hospitals, structurally equivalent social networks are more important in predicting subcultures than are hierarchical groupings and hierarchy has a limited impact on the development of verbal networks. These findings suggest the value of an amoeba rather than a pyramid metaphor in interpreting the cultures and relational structures of organizations.