Noncontiguous operon atlas for the Staphylococcus aureus genome.

Bacteria synchronize the expression of genes with related functions by organizing genes into operons so that they are cotranscribed together in a single polycistronic messenger RNA. However, some cellular processes may benefit if the simultaneous production of the operon proteins coincides with the inhibition of the expression of an antagonist gene. To coordinate such situations, bacteria have evolved noncontiguous operons (NcOs), a subtype of operons that contain one or more genes that are transcribed in the opposite direction to the other operon genes. This structure results in overlapping transcripts whose expression is mutually repressed. The presence of NcOs cannot be predicted computationally and their identification requires a detailed knowledge of the bacterial transcriptome. In this study, we used direct RNA sequencing methodology to determine the NcOs map in the Staphylococcus aureus genome. We detected the presence of 18 NcOs in the genome of S. aureus and four in the genome of the lysogenic prophage 80α. The identified NcOs comprise genes involved in energy metabolism, metal acquisition and transport, toxin-antitoxin systems, and control of the phage life cycle. Using the menaquinone operon as a proof of concept, we show that disarrangement of the NcO architecture results in a reduction of bacterial fitness due to an increase in menaquinone levels and a decrease in the rate of oxygen consumption. Our study demonstrates the significance of NcO structures in bacterial physiology and emphasizes the importance of combining operon maps with transcriptomic data to uncover previously unnoticed functional relationships between neighbouring genes.

Bioconversion of lignin-derived aromatics into the building block pyridine 2,4-dicarboxylic acid by engineering recombinant Pseudomonas putida strains.

2,4 pyridine dicarboxylic acid (2,4 PDCA) is an analogue of terephthalate, and hence a target chemical in the field of bio-based plastics. Here, Pseudomonas putida KT2440 strains were engineered to efficiently drive the metabolism of lignin-derived monoaromatics towards 2,4 PDCA in a resting cells-based bioprocess that alleviates growth-coupled limitations and allows biocatalysts recycling. Native ß-ketoadipate pathway was blocked by replacing protocatechuate 3,4-dioxygenase by the exogenous LigAB extradiol dioxygenase. Overexpression of pcaK encoding a transporter increased 8-fold 2,4 PDCA productivity from protocatechuate, reaching the highest value reported so far (0.58 g L-1h-1). Overexpression of the 4-hydroxybenzoate monooxygenase (pobA) speed up drastically the production of 2,4 PDCA from 4-hydroxybenzoate (0.056 g L-1h-1) or p-coumarate (0.012 g L-1h-1) achieving values 15-fold higher than those reported with Rhodococcus jostii biocatalysts. 2,4 PDCA was also bioproduced by using soda lignin as feedstock, paving the way for future polymeric lignin valorization approaches.

Eventos estresantes asociados al inicio y exacerbación de síntomas en pacientes con artritis reumatoide / The stressors events related to exacerbated the symptoms in rheumatoid arthritis patients

En una muestra de 24 mujeres con artritis reumatoide (AR) se evaluó la existencia de eventos estresantes al cominezo de la enfermedad y el tipo de eventos que acentuaban sus síntomas; así también, se registró en qué medida se daban los eventos estresantes en relación con la presencia de familiar AR. Se clasificó al grupo de pacientes en seropositivas y seronegativas, y de acuerdo al inicio progresivo o agudo de la AR, relacionándose también el subtipo de AR, con los valores de velocidad de sedimentación globular y la presencia de agregación familiar. Luego, en una muestra mayor, de 40 pacientes AR, se exploró nuevamente la incidencia que factores psicológicos tuvieron al comienzo y en la exacerbación de la AR. No se encontró ninguna asociación significativa entre las variables que fueron seleccionadas

Estado actual de la historia de la psicología en México / Current state of the history of psychology in Mexico

Hemos querido contribuir mostrando un esbozo del estado en que se encuentra actualmente la historia de la psicología mexicana Sin embargo, creemos que nuestra principal contribuición es difundir una guía bibliográfica sobre la producción generada en este campo. Ella permirá a los interesados en el área tener una base de la cual partir, facilitando así su labor y promoviendo el estudio de nuevos temas con nuevos métodos, evitando con ello la reiteración temática y el empantamiento de esta especialidad.