The use of protein hydrolysate improves the protein intestinal absorption in undernourished mice infected with Schistosoma mansoni

Patients residing in endemic areas for schistosomiasis in Brazil are usually undernourished and when they develop the hepatosplenic clinical form of the disease should usually receive hospital care, many of them being in need of nutritional rehabilitation before specific treatment can be undertaken. In the mouse model, investigations carried out in our laboratory detected a reduced aminoacid uptake in undernourished animals which is aggravated by a superimposed infection with Schistosoma mansoni. However, in well-nourished infected mice no dysfunction occurs. In this study, we tried to improve the absorptive intestinal performance of undernourished mice infected with S. mansoni by feeding them with hydrolysed casein instead of whole casein. The values obtained for the coefficient of protein intestinal absorption (cpia) among well-nourished mice were above 90% (either hydrolysed or whole protein). In undernourished infected mice, however, the cpia improved significantly after feeding them with hydrolysed casein, animals reaching values close to those obtained in well-nourished infected mice.

Structural changes in the jejunal mucosa of mice infected with Schistosoma mansoni, fed low or high protein diets

The effects of high and low-protein diets on the structure of the jejunal mucosa were studied in Schistosoma mansoni infected mice (morphology and histomorphometry). Weaning male albino mice were infected with 80 cercariae, fed with high (20%) or low-protein (5%) diets and compared to uninfected controls under the same conditions. Mice were sacrificed 12 weeks after infection. Animals submitted to a low-protein diet showed lower weight curves, mainly when infected. In the jejunal mucosa, finger-like villi were the predominant pattern among uninfected high-protein fed animals, while the infected ones showed leaf-shaped and flattened villi in most cases. Undernourished infected mice had 65.7% leaf-shaped villi. A significant increase in the number of goblet cells was seen in infected mice. A decrease in the number of absorptive cells was detected in undernourished mice, particularly in infected ones.

Dissecting the function of the SpoIIIJ and YqjG membrane protein insertases during bacterial spore development

Dissertation presented to obtain the Ph.D degree in Biology, Microbial Biology

Variation in protein expression levels in cell populations

Dissertation presented to obtain the Ph.D degree in Systems Biology

Production of septal fibrosis of the liver by means of foreign protein injections into rats

Similarities and differences in antigenic humoral responses and electrophoretic patterns between Capillaria hepatica and pig-serum were investigated as a contribution to the understanding of hepatic fibrosis induced by the parenteral administration of foreign proteins. Only two out of 10 rats receiving repeated intraperitoneal injections of an extract of Capillaria hepatica-infected mouse liver presented septal hepatic fibrosis (20%). Under the same experimental conditions, 4 out of 9 rats (44.4%) developed septal fibrosis following whole pig-serum administration. Injections of normal mouse liver extracts did not result in hepatic fibrosis. Since a 100% septal fibrosis rate is observed in experimentally Capillaria hepatica-infected rats, it appeared that Capillaria hepatica products continuously released from inside the liver creates a much more effective fibrosis inducing mechanism than the parenteral administration of such factors. Thus, repeated peritoneal administration of a foreign protein to rats would not reveal the full fibrogenic potential it may have under natural conditions.

DNA-Protein interaction: a response regulatory protein associated with Mo homeostasis in Desulfovibrio alaskensis G20.

Dissertation for a degree in Doctor in Sustainable Chemistry

Functional and structural studies of a mini-ferritin protein

Dissertação para obtenção do Grau de Mestre em Bioquímica

Bioinspired polyethersulfone-based hollow fiber membranes as the scaffolds in renal assist device for protein-bound toxins removal from blood

Dissertation for obtaining the Master degree in Membrane Engineering

Assessment of Notch1 ligands production - key protein targets in breast cancer

Cell-to-cell communication is required for many biological processes in development and adult life. One of the most common systems utilized by a wide range of eukaryotes is the Notch signalling pathway. Four Notch receptors and five ligands have been identified in mammals that interact via their extracellular domains leading to transcription activation. Studies have shown that the Notch ligands expression is undetectable in normal breast tissues, but moderate to high expression has been detected in breast cancer. Thus, any of the Notch1 ligands can be studied as possible therapeutic targets for breast cancer. To study Notch pathway proteins there is the need to obtain stable protein solutions. E. coli is the host of excellence for recombinant proteins for the ease of use, fast growth and high cell densities. However, the expression of mammalian proteins in such systems may overwhelm the bacterial cellular machinery, which does not possess the ability for post-translational modifications, or dedicated compartments for protein synthesis. Mammalian cells are therefore preferred, despite their technical and financial increased demands. We aim to determine the best expression and purification conditions for the different ligand protein constructs, to develop specific function-blocking antibodies using the Phage Display technology. Moreover, we propose to crystallize the Notch1 ligands alone and in complex with the phage display selected antibodies, unveiling molecular details. hJag2DE3 and hDll1DE6 proteins were purified from refolded inclusion bodies or mammalian cell culture supernatants, respectively, and purity was confirmed by SDS-PAGE (>95%). Protein produced in mammalian cells showed to be more stable, apparently with the physiological disulfide pattern, contrary to what was observed in the refolded protein. Several nano-scale crystallization experiments were set up in 96-well plates, but no positive result was obtained. We will continue to pursue for the best expression for the Notch ligand constructs in both expression systems.

Assembly and function of a protein cross-linking enzyme during bacterial spore morphogenesis

Sporulation in Bacillus subtilis culminates with the formation of a dormant endospore. The endospore (or spore) is one of the most resilient cell types known and can remain viable in the environment for extended periods of time. Contributing to the spore’s resistance and its ability to interact with and monitor its immediate environment is the coat, the outermost layer of B. subtilis spores. The coat is composed by over 70 different proteins, which are produced at different stages in sporulation and orderly assembled around the developing spore.(...)

PROTEIN FOLDING AND DISEASE THE MITOCHONDRIAL PROTEIN FRATAXIN

This dissertation focuses on the study of frataxin, a small mitochondrial protein whose deficiency is associated with the neurodegenerative disease Friedreich's ataxia (FRDA). Aiming at a better understanding of frataxin conformational and functional properties, two lines of research were followed: first, the effect of FRDA-related mutations in human frataxin (FXN) were studied and the role of oxidative stress related modification addressed; second, yeast frataxin (Yfh1) orthologue was used to explore the conformational and functional properties of the protein.(...)

Manipulation of host cell functions by Salmonella: the role of the bacterial effector protein SteA

Salmonella enterica serovars are Gram-negative facultative intracellular bacterial pathogens that infect a wide variety of animals. Salmonella infections are common in humans, causing usually typhoid fever and gastrointestinal diseases. Salmonella enterica serovar Typhimurium (S. Typhimurium), which is a leading cause of human gastroenteritis, has been extensively used to study the molecular pathogenesis of Salmonella, because of the availability of sophisticated genetic tools, and of suitable animal and tissue culture models mimicking different aspects of Salmonella infections.(...)

Inhibition of SNF1-related protein kinase1 by trehalose 6-phosphate and other metabolites and the interrelation with plant gorwth

All life forms need to monitor carbon and energy availability to survive and this is especially true for plants which must integrate unavoidable environmental conditions with metabolism for cellular homeostasis maintenance. Sugars, in the heart of metabolism, are now recognized as crucial signaling molecules that translate those conditions. One such signal is trehalose 6- phosphate (T6P), a phosphorylated dimer of glucose molecules which levels correlate well with those of sucrose (Suc). Central integrators of stress and energy regulation include the conserved plant Snf1-related kinase1 (SnRK1) which respond to low cellular energy levels by up-regulating energy conserving and catabolic metabolism and down-regulating energy consuming processes. In 2009 T6P was shown to inhibit SnRK1. The in vitro inhibition of SnRK1 by T6P was confirmed in vivo through the observation that genes normally induced by SnRK1 were repressed by T6P and vice-versa, promoting growth processes. These observations provided a model for the regulation of growth by sugar.(...)