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Search Results: 1 - 10 of 220049 matches for " Georgia C. Atella "
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Optimization of Nitrogen, Phosphorus and Salt for Lipid Accumulation of Microalgae: Towards the Viability of Microalgae Biodiesel  [PDF]
Carolina T. Miranda, Daniel V. N. de Lima, Georgia C. Atella, Paula F. de Aguiar, Sandra M. F. O. Azevedo
Natural Science (NS) , 2016, DOI: 10.4236/ns.2016.812055
Abstract:
In recent years, microalgae biodiesel has attracted expressive attention and investment, once it was considered a potential resource for energy. Although the wide use of microalgae biodiesel is restricted by its high production cost. For cost-efficient and sustainable production of biodiesel from microalgae, a proper understanding of the variables and their impacts on physiology of the strains is required. In this study, a simple factorial design 23 was used to find optimal conditions for the cultivation of Ankistrodesmus sp. and Chlamydomonas sp. in batch culture. The three components considered were nitrate, phosphate and sodium chloride, used to assess the metabolic versatility of the strains in brackish conditions. The results showed that culture medium with 0.04 g·L?1 nitrate, 0.01 g·L?1 phosphate and 5.0 g·L?1 sodium chloride resulted to be the most effective condition to growth and fatty acids accumulation. Using this optimal condition, Ankistrodesmus sp. and Chlamydomonas sp. increased in 2.1 and 2.4 folds their fatty acids yield, respectively. Importantly, this protocol reduced 75% of the nitrate and phosphate concentrations of the original medium (ASM-1). Additionally, fatty acids analysis found that these strains were mainly constituted of C16-C18, in accordance with the requirements for biodiesel production. The simple factorial design applied here proved to be an important tool towards a better understanding of synergistic effects of tested factors on microalgae metabolism, and the resulting information could be used effectively to improve microalgae cultivation.
Oogenesis and egg development in triatomines: a biochemical approach
Atella Georgia C.,Gondim Katia C.,Machado Ednildo A.,Medeiros Marcelo N.
Anais da Academia Brasileira de Ciências , 2005,
Abstract: In triatomines, as well as in other insects, accumulation of yolk is a process in which an extra-ovarian tissue, the fat body, produces yolk proteins that are packed in the egg. The main protein, synthesized by the fat body, which is accumulated inside the oocyte, is vitellogenin. This process is also known as vitellogenesis. There are growing evidences in triatomines that besides fat body the ovary also produces yolk proteins. The way these yolk proteins enter the oocyte will be discussed. Yolk is a complex material composed of proteins, lipids, carbohydrates and other minor components which are packed inside the oocyte in an organized manner. Fertilization triggers embryogenesis, a process where an embryo will develop. During embryogenesis the yolk will be used for the construction of a new individual, the first instar nymph. The challenge for the next decade is to understand how and where these egg proteins are used up together with their non-protein components, in pace with the genetic program of the embryo, which enables cell differentiation (early phase of embryogenesis) and embryo differentiation (late phase) inside the egg.
Transferrin uptake may occur through detergent-resistant membrane domains at the cytopharynx of Trypanosoma cruzi epimastigote forms
Corrêa, José R;Atella, Georgia C;Vargas, Camila;Soares, Maurilio J;
Memórias do Instituto Oswaldo Cruz , 2007, DOI: 10.1590/S0074-02762007005000117
Abstract: uptake of transferrin by epimastigote forms of the protozoan trypanosoma cruzi occurs mainly through a cytostome/ cytopharynx, via uncoated endocytic vesicles that bud off from the bottom of the cytopharynx. we have here examined whether detergent-resistant membrane (drm) domains might be involved in this process. purified whole cell membrane fractions were assayed for cholesterol levels and used in dot blot analyses. detergent-resistant membrane markers (cholera b toxin and anti-flotillin-1 antibody) presented positive reaction by dot blots in cholesterol-rich/ protein-poor membrane sub-fractions. the positive dot blot fraction was submitted to lipid composition analysis, showing composition similar to that of raft fractions described for other eukaryotic cells. immunofluorescence assays allowed the localization of punctual positive signal for flotillin-1, matching the precise cytostome/ cytopharynx location. these data were confirmed by immunofluorescence assays with the co-localization of flotillin-1 and the transferrin uptake site. our data suggest that drm domains occur and are integrated at the cytostome/ cytopharynx of t. cruzi epimastigotes, being the main route for transferrin uptake.
Lysophosphatidylcholine: A Novel Modulator of Trypanosoma cruzi Transmission
Mário A. C. Silva-Neto,Alan B. Carneiro,Livia Silva-Cardoso,Georgia C. Atella
Journal of Parasitology Research , 2012, DOI: 10.1155/2012/625838
Abstract: Lysophosphatidylcholine is a bioactive lipid that regulates a large number of cellular processes and is especially present during the deposition and infiltration of inflammatory cells and deposition of atheromatous plaque. Such molecule is also present in saliva and feces of the hematophagous organism Rhodnius prolixus, a triatominae bug vector of Chagas disease. We have recently demonstrated that LPC is a modulator of Trypanosoma cruzi transmission. It acts as a powerful chemoattractant for inflammatory cells at the site of the insect bite, which will provide a concentrated population of cells available for parasite infection. Also, LPC increases macrophage intracellular calcium concentrations that ultimately enhance parasite invasion. Finally, LPC inhibits NO production by macrophages stimulated by live T. cruzi, and thus interferes with the immune system of the vertebrate host. In the present paper, we discuss the main signaling mechanisms that are likely used by such molecule and their eventual use as targets to block parasite transmission and the pathogenesis of Chagas disease. 1. Immune Response to Trypanosoma cruzi Infection in the Vertebrate Host T. cruzi infects the vertebrate host through bite wounds produced in skin by a feeding bug or through the interaction of the parasite with conjunctival mucosa. Such interaction sometimes produces visible signs called Roma?a’s sign or chagoma inoculation. The histology of this initial site of infection is defined by an elevated number of mononuclear cells [1]. This first sign of infection suggests that T. cruzi can stimulate skin cells to produce mediators that trigger a local inflammatory response. Despite controversies about the mechanism of the pathogenesis of Chagas disease [2–5], until recently, some authors believed that the disease was limited to an acute phase, followed by a chronic phase that was considered an autoimmune disease, where the parasites would be physically linked to sites of inflammation in the heart and esophagus [6–8]. However, nowadays, the disease is considered multifactorial, with multiple and continuous interactions between pathogen and host [9]. After the incubation period of 2 to 3 weeks, infection with T. cruzi is manifested by the presence of a large number of parasites in the blood and tissues. Acute infection is accompanied by an excessive activation of the immune system that includes the production of high levels of cytokines, intense activation of T and B cells, lymphadenopathy, splenomegaly, and intense inflammation associated with tissue infection niches. The acute
Oogenesis and egg development in triatomines: a biochemical approach
Atella, Georgia C.;Gondim, Katia C.;Machado, Ednildo A.;Medeiros, Marcelo N.;Silva-Neto, Mário A.C.;Masuda, Hatisaburo;
Anais da Academia Brasileira de Ciências , 2005, DOI: 10.1590/S0001-37652005000300005
Abstract: in triatomines, as well as in other insects, accumulation of yolk is a process in which an extra-ovarian tissue, the fat body, produces yolk proteins that are packed in the egg. the main protein, synthesized by the fat body, which is accumulated inside the oocyte, is vitellogenin. this process is also known as vitellogenesis. there are growing evidences in triatomines that besides fat body the ovary also produces yolk proteins. the way these yolk proteins enter the oocyte will be discussed. yolk is a complex material composed of proteins, lipids, carbohydrates and other minor components which are packed inside the oocyte in an organized manner. fertilization triggers embryogenesis, a process where an embryo will develop. during embryogenesis the yolk will be used for the construction of a new individual, the first instar nymph. the challenge for the next decade is to understand how and where these egg proteins are used up together with their non-protein components, in pace with the genetic program of the embryo, which enables cell differentiation (early phase of embryogenesis) and embryo differentiation (late phase) inside the egg.
Allosteric regulation of 6-phosphofructo-1-kinase activity of fat body and flight muscle from the bloodsucking bug Rhodnius prolixus
Alves, Gutemberg G.;Marinho-Carvalho, Monica M.;Atella, Georgia C.;Silva-Neto, Mario A.C.;Sola-Penna, Mauro;
Anais da Academia Brasileira de Ciências , 2007, DOI: 10.1590/S0001-37652007000100008
Abstract: 6-phosphofructo-1-kinase (phosphofructokinase; pfk) activity from rhodnius prolixus, a haematophagous insect which is usually a poor flyer, was measured and compared in two metabolically active tissues - flight muscle and fat body. the activity of this important regulatory glycolytic enzyme was much more pronounced in muscle (15.1 ± 1.4 u/mg) than in fat body extracts (3.6±0.4 u/mg), although the latter presented higher levels of enzyme per protein content, as measured by western-blotting. muscle extracts are more responsible than fat body to atp and fructose 6-phosphate, both substrates of pfk. allosteric regulation exerted by different effectors such as adp, amp and fructose 2,6-phosphate presented a singular pattern for each tissue. optimal ph (8.0-8.5) and sensitivity to ph variation was very similar, and citrate was unable to inhibit pfk activity in both extracts. our results suggest the existence of a particular pfk activity for each tissue, with regulatory patterns that are consistent with their physiological roles.
Trypanosoma cruzi Epimastigotes Are Able to Store and Mobilize High Amounts of Cholesterol in Reservosome Lipid Inclusions
Miria G. Pereira, Ernesto S. Nakayasu, Celso Sant'Anna, Nuccia N. T. De Cicco, Georgia C. Atella, Wanderley de Souza, Igor C. Almeida, Narcisa Cunha-e-Silva
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0022359
Abstract: Background Reservosomes are lysosome-related organelles found in Trypanosoma cruzi epimastigotes. They represent the last step in epimastigote endocytic route, accumulating a set of proteins and enzymes related to protein digestion and lipid metabolism. The reservosome matrix contains planar membranes, vesicles and lipid inclusions. Some of the latter may assume rectangular or sword-shaped crystalloid forms surrounded by a phospholipid monolayer, resembling the cholesterol crystals in foam cells. Methodology/Principal Findings Using Nile Red fluorimetry and fluorescence microscopy, as well as electron microscopy, we have established a direct correlation between serum concentration in culture medium and the presence of crystalloid lipid inclusions. Starting from a reservosome purified fraction, we have developed a fractionation protocol to isolate lipid inclusions. Gas-chromatography mass-spectrometry (GC-MS) analysis revealed that lipid inclusions are composed mainly by cholesterol and cholesterol esters. Moreover, when the parasites with crystalloid lipid-loaded reservosomes were maintained in serum free medium for 48 hours the inclusions disappeared almost completely, including the sword shaped ones. Conclusions/Significance Taken together, our results suggest that epimastigote forms of T. cruzi store high amounts of neutral lipids from extracellular medium, mostly cholesterol or cholesterol esters inside reservosomes. Interestingly, the parasites are able to disassemble the reservosome cholesterol crystalloid inclusions when submitted to serum starvation.
An Insight into the Transcriptome of the Digestive Tract of the Bloodsucking Bug, Rhodnius prolixus
José M. C. Ribeiro ,Fernando A. Genta,Marcos H. F. Sorgine,Raquel Logullo,Rafael D. Mesquita,Gabriela O. Paiva-Silva,David Majerowicz,Marcelo Medeiros,Leonardo Koerich,Walter R. Terra,Clélia Ferreira,André C. Pimentel,Paulo M. Bisch,Daniel C. Leite,Michelle M. P. Diniz,Jo?o Lídio da S. G. V. Junior,Manuela L. Da Silva,Ricardo N. Araujo,Ana Caroline P. Gandara,Sébastien Brosson,Didier Salmon,Sabrina Bousbata,Natalia González-Caballero,Ariel Mariano Silber,Michele Alves-Bezerra,Katia C. Gondim,Mário Alberto C. Silva-Neto,Georgia C. Atella,Helena Araujo,Felipe A. Dias,Carla Polycarpo,Raquel J. Vionette-Amaral,Patrícia Fampa,Ana Claudia A. Melo,Aparecida S. Tanaka,Carsten Balczun,José Henrique M. Oliveira,Renata L. S. Gon?alves,Cristiano Lazoski,Rolando Rivera-Pomar,Luis Diambra,Günter A. Schaub,Elói S. Garcia,Patrícia Azambuja,Glória R. C. Braz ,Pedro L. Oliveira
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0002594
Abstract: The bloodsucking hemipteran Rhodnius prolixus is a vector of Chagas' disease, which affects 7–8 million people today in Latin America. In contrast to other hematophagous insects, the triatomine gut is compartmentalized into three segments that perform different functions during blood digestion. Here we report analysis of transcriptomes for each of the segments using pyrosequencing technology. Comparison of transcript frequency in digestive libraries with a whole-body library was used to evaluate expression levels. All classes of digestive enzymes were highly expressed, with a predominance of cysteine and aspartic proteinases, the latter showing a significant expansion through gene duplication. Although no protein digestion is known to occur in the anterior midgut (AM), protease transcripts were found, suggesting secretion as pro-enzymes, being possibly activated in the posterior midgut (PM). As expected, genes related to cytoskeleton, protein synthesis apparatus, protein traffic, and secretion were abundantly transcribed. Despite the absence of a chitinous peritrophic membrane in hemipterans - which have instead a lipidic perimicrovillar membrane lining over midgut epithelia - several gut-specific peritrophin transcripts were found, suggesting that these proteins perform functions other than being a structural component of the peritrophic membrane. Among immunity-related transcripts, while lysozymes and lectins were the most highly expressed, several genes belonging to the Toll pathway - found at low levels in the gut of most insects - were identified, contrasting with a low abundance of transcripts from IMD and STAT pathways. Analysis of transcripts related to lipid metabolism indicates that lipids play multiple roles, being a major energy source, a substrate for perimicrovillar membrane formation, and a source for hydrocarbons possibly to produce the wax layer of the hindgut. Transcripts related to amino acid metabolism showed an unanticipated priority for degradation of tyrosine, phenylalanine, and tryptophan. Analysis of transcripts related to signaling pathways suggested a role for MAP kinases, GTPases, and LKBP1/AMP kinases related to control of cell shape and polarity, possibly in connection with regulation of cell survival, response of pathogens and nutrients. Together, our findings present a new view of the triatomine digestive apparatus and will help us understand trypanosome interaction and allow insights into hemipteran metabolic adaptations to a blood-based diet.
Children Friendship: The Role of Hope in Attributions, Emotions and Expectations  [PDF]
Georgia Stephanou
Psychology (PSYCH) , 2011, DOI: 10.4236/psych.2011.28133
Abstract: This research aimed to examine a) children’s attributions and emotions for their subjectively perceived friendships with their best friends as positive or negative, b) the role of children’s hope (pathways thinking, agency thinking) in the generation of their perception of their friendships as positive or negative, in the formulation of the subsequent attributions and emotions, and in the impact of attributions on emotions, and c) the effects of hope in the interactive impact of attributions and emotions on friendship expectations. The participants were 322 children, both gender, 5th and 6th grades, representing various parental socioeconomic levels. The results showed that the perceived satisfactory friendships were mainly attributed to internal, and self-friend interactive internal and controllable factors, while the estimated as non satisfactory friendships were predominately attributed to stable, friend’s controllable and internal, and self-friend interactive internal factors. The children experienced intense positive and negative emotions for their perceived satisfactory and non satisfactory friendships, respectively. Hope (mostly, agency thinking) positively influenced the generation of the perceived quality of the friendship, the subsequent attributions (particularly, stability) and emotions, and the impact of attributions on emotions, mainly in the negative friendships group. Also, in the positive friendship group, high-pathway thinking children had higher expectations of positive friendship, whereas, in the non satisfactory friendship group, low-agency thinking children had low expectations of positive friendship. Finally, hope proved formulator of the interactive effect of attributions (mainly, locus of causality) and emotions on friendship expectations. The findings from this study suggest the significant role of good friendship in children’s life, and indicate the importance of examining children friendship along the role of hope in evaluating, attributing causes, experiencing emotions and forming expectations.
Romantic Relationships in Emerging Adulthood: Perception-Partner Ideal Discrepancies, Attributions, and Expectations  [PDF]
Georgia Stephanou
Psychology (PSYCH) , 2012, DOI: 10.4236/psych.2012.32023
Abstract: This study aimed to examine 1) emerging adults’ attributions for their subjectively perceived current ro- mantic relationship as good or bad, 2) the role of their perception-partner ideal discrepancies in estimate- ing their current romantic relationship as good or bad, and in the formation of attributions, and 3) the ef- fects of all the three concepts on the generation of the expectations for the quality of the romantic rela- tionship in the future. Undergraduate and postgraduate university students, from various faculties, ages of 18 to 25, both genders, participated in this study. The participants filled in, first, the scale of the romantic partner ideals, and, after one week, the scales of perceived of the quality of the current romantic relation- ship, attributions and expectations. The results regarding attributions revealed that 1) the perceived good romantic relationships were mainly attributed to internal and self-partner internal and controllable factors (love, passion, effective communication, honesty-loyalty, understanding each-other), whereas the per- ceived bad romantic relationships were mainly attributed to personal uncontrollable, external, unstable and partner’s internal factors (untrustworthiness, lack of passion, non honesty-loyalty, lack of love, and ineffective communication), and 2) locus of causality, followed by personal controllability and stability, was the most powerful attributional dimension in discriminating the two groups of the emerging adults. The findings regarding the perception-partner ideal discrepancy showed that 1) the students who had smaller perception-partner ideal discrepancy, compared to students who had larger perception-partner ideal discrepancy, estimated their current romantic relationships more favourable but only trustworthiness accounted for unique variance in it and 2) perception-partner ideal discrepancy in trustworthiness, fol- lowed by warmth/intimacy, and attractiveness/vitality, was the most powerful factor in discriminating the two groups of the participants. The results with respect to effects of partner ideal discrepancy on attributions indicated that 1) the students’ perception-partner ideal discrepancies proved to be a significant and positive factor in the formulation of the attributional dimensions (expect for external controllability), mainly both stability and locus of causality, for the perceived current quality of their romantic relationship and 2) only trustworthiness and warmth/intimacy had unique effects on locus of causality, and only trustworthiness uniquely contributed into
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