Improved RNA modification mapping through complementary nucleobase-specific ribonucleases.

The human immunodeficiency virus type 1 (HIV-1) encodes multiple RNA molecules. Transcripts that originate from the proviral 5’ long terminal repeat (LTR) function as messenger RNAs for the expression of 16 different mature viral proteins. In addition, HIV-1 expresses an antisense tran-script (Ast) from the 3’LTR, which has both protein-coding and noncoding properties. While the mechanisms that regulate the coding and noncoding activities of Ast remain unknown, post-transcriptional modifications are known to influence RNA stability, interaction with protein part-ners, and translation capacity. Here we report the nucleoside modification profile of Ast obtained through liquid chromatography coupled with mass spectrometry (LC-MS) analysis. The epitran-scriptome includes a limited set of modified nucleosides but predominantly ribose methylations. A number of these modifications were mapped to specific positions of the sequence through RNA modification mapping procedures. The presence of modifications on Ast is consistent with the RNA-modifying enzymes interacting with Ast. The identification and mapping of Ast post-transcriptional modifications is expected to elucidate the mechanisms through which this versa-tile molecule can carry out diverse activities in different cell compartments. Manipulation of post-transcriptional modifications on the Ast RNA may have therapeutic implications.

Oxidative stress triggered by the Fenton reaction (chemical) or UVR exposure (photo) can damage cellular biomolecules including RNA through oxidation of nucleotides. Besides such xenobiotic chemical modifications, RNA also contains several post-transcriptional nucleoside modifications that are installed by enzymes to modulate structure, RNA-protein interactions, and biochemical functions. We examined the extent of oxidative damage to naturally modified RNA which is required for cellular protein synthesis under two different contexts. The extent of oxidative damage is higher when RNA is not associated with proteins, but the degree of damage is lower when the RNA is presented in the form of a ribonucleoprotein complex, such as an intact ribosome. Our studies also indicate that absence of methylations in ribosomal RNA at specific positions could make it more susceptible to photooxidative stress. However, the extent of guanosine oxidation varied with the position at which the modification is deficient, indicating position-dependent structural effects. Further, an E. coli strain deficient in 5-methylaminomethyl-2-thiouridine (mnm5s2U) (found in lysine and glutamate tRNA anticodon) is more vulnerable to oxidative RNA damage compared to its wildtype strain suggesting an auxiliary function for the mnm5s2U modification. These studies indicate that oxidative damage to RNA is altered by the presence of enzymatic modified nucleosides or protein association inside the cell.

Introduction: There is evidence about the close relationship between chronic non-communicable diseases, eating habits and physical activity. Based on the results of the 4th National Survey of Risk Factors (ENFR), an island territory in the province of Buenos Aires was sought where it was assumed that the way of life could have a positive influence. Objectives: to analyze the frequency of habits, the frequency of chronic pathologies and the relationship between them; assuming that a lifestyle away from the big cities would lead to healthier habits, and with it, better health indicators. Material and methods: Prevalence study. A house-to-house survey of 42 homes on Santiago Island, where a survey and physical examination were applied, which included: anthropometric measurements, blood pressure, and capillary blood glucose. Results: Most of the dwellings (71.4%) had fruit trees or orchards in their homes at the time of data collection. However, when making the comparison with the 4th ENFR, the results showed that it was a population in which physical inactivity, poor diet and problematic consumption of alcohol and tobacco exceeded the national average. Chronic diseases resulted in a trend similar to the national one. Conclusions: Although accessibility to resources should be considered an important element, this characteristic is added to87 others due to associated factors such as sociocultural, advertising and aspects of health education. The importance of working deeply on population habits is highlighted, as well as emphasizing the need to implement efficient educational programs with a local perspective. Key words: Cardiovascular risk factors; chronic non-communicable diseases; nutritional habits.