New insights into trypanosomatid U5 small nuclear ribonucleoproteins

Several protozoan parasites exist in the Trypanosomatidae family, including various agents of human diseases. Multiple lines of evidence suggest that important differences are present between the translational and mRNA processing (trans splicing) systems of trypanosomatids and other eukaryotes. In this context, certain small complexes of RNA and protein, which are named small nuclear ribonucleoproteins (U snRNPs), have an essential role in pre-mRNA processing, mainly during splicing. Even though they are well defined in mammals, snRNPs are still not well characterized in trypanosomatids. This study shows that a U5-15K protein is highly conserved among various trypanosomatid species. Tandem affinity pull-down assays revealed that this protein interacts with a novel U5-102K protein, which suggests the presence of a sub-complex that is potentially involved in the assembly of U4/U6-U5 tri-snRNPs. Functional analyses showed that U5-15K is essential for cell viability and is somehow involved with the trans and cis splicing machinery. Similar tandem affinity experiments with a trypanonosomatid U5-Cwc21 protein led to the purification of four U5 snRNP specific proteins and a Sm core, suggesting U5-Cwc-21 participation in the 35S U5 snRNP particle. Of these proteins, U5-200K was molecularly characterized. U5-200K has conserved domains, such as the DEAD/DEAH box helicase and Sec63 domains and displays a strong interaction with U5 snRNA.

Sorotipos e virulência de Salmonella sp. isolada de água doce / Serotypes and virulence of Salmonella sp. isolated from fresh water

A partir de amostras de água doce isolaram-se 26 cepas de Salmonella sp. de sorotipos diversos. A presença de plasmídios foi verificada nessas amostras sendo que onze delas apresentavam plasmídios de diferentes pesos moleculares. Quatro amostras contendo plasmídios e duas sem plasmídios foram analisadas quanto à capacidade de invasäo em camundongos. Com respeito a S. typhimurium, é possível sugerir uma correlaçäo entre virulência e a presença de plasmídio.

The cDNA cloning control expression of growth control genes

Cell proliferation is controlled by classical hormones and peptide growth factors. Uncontrolled, neoplastic growth is characterized by abrogation of the cell's requirement for extracellular regulators. Steroid hormones and serum growth factors have been shown to alter the cell's transcriptional program. fos and jun are immediate early genes induced by serum growth factors. Fos and Jun proteins interact with other proteins and with DNA, thus modulating the activity of both the glucocorticoid receptor and of genes directly related to DNA synthesis and cell division. To better understand the molecular basis for growth control and the anti-inflammatory and antitumor effects of glucocorticoid hormones, we here describe: a) cloning of cDNA sequences regulated by glucocorticoids in a rat glioma cell line that reversibly reacts to hormone treatment by changing from a transformed, malignant phenotype to normal; b) expression of the c-fos proto-oncogene in the eukaryotic baculovirus expression system.