Mycobacterium colombiense is a novel member of the Mycobacterium avium complex, which produces respiratory and disseminated infections in immunosuppressed patients. Currently, the morphological and genetic bases underlying the phenotypic features of M. colombiense strains remain unknown. In the present study, we demonstrated that M. colombiense strains displaying smooth morphology show increased biofilm formation on hydrophobic surfaces and sliding on motility plates. Thin-layer chromatography experiments showed that M. colombiense strains displaying smooth colonies produce large amounts of glycolipids with a chromatographic behaviour similar to that of the glycopeptidolipids (GPLs) of M. avium. Conversely, we observed a natural rough variant of M. colombiense (57B strain) lacking pigmentation and exhibiting impaired sliding, biofilm formation, and GPL production. Bioinformatics analyses revealed a gene cluster that is likely involved in GPL biosynthesis in M. colombiense CECT 3035. RT-qPCR experiments showed that motile culture conditions activate the transcription of genes possibly involved in key enzymatic activities of GPL biosynthesis.
Among the 12 P-type ATPases encoded by the genome of Mycobacterium tuberculosis(Mtb), CtpF responds to the greatest number of stress conditions, including oxidative stress, hypoxia, and infection. CtpF is the mycobacterial homolog of the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) of higher eukaryotes. Its expression is regulated by the global regulator of latency, DosR. However, the role that CtpF plays in the mycobacterial plasma membrane remains unknown. In this study, different functional analyses showed that CtpF is associated with calcium pumping from mycobacterial cells. Specifically, Mtb CtpF expression in Mycobacterium smegmatis cells prevents Ca2+ accumulation compared with wild type (WT) cells. In addition, plasma membrane vesicles from recombinant membranes, in which the direction of ion transport is inverted, accumulate more Ca2+ compared with vesicles obtained from the WT strain. This findings support the hypothesis that CtpF contributes to calcium efflux from mycobacterial cells. Accordingly, Mtb cells defective in ctpF (MtbΔctpF) accumulate more Ca2+ compared with WT cells, while the Ca2+-dependent ATPase activity is significantly lower in the mutant cells. Interestingly, the deletion of ctpF in Mtb impairs the tolerance of the bacteria to oxidative and nitrosative stress. Overall, our results indicate that CtpF is associated with calcium pumping from mycobacterial cells and the response to oxidative stress.
Background: The COVID-19 pandemic forced the implementation of global emergency measures based on social distancing. In Colombia, remote classes in universities have avoided the spread of the disease. However, the implementation of remote classes demands virtual pedagogical strategies that are not traditionally used for teaching basic sciences in the Colombian public education system. This study describes student perception of remote biochemistry classes at Universidad Nacional de Colombia (Bogota).Methods: A virtual survey was applied to undergraduate students of dentistry and biology programs to assess their perception of the quality and academic impact of remote classes during the mandatory lockdown decreed by the Colombian government for semester I of 2020. Results: The students demonstrated an overall acceptance of the remote biochemistry classes, highlighting that the quality of the classes facilitated the understanding of the topics, increased assessment performance, and significantly promoted self-learning (according to 84.6% of the respondents). Although some students reported having experienced reduced attention to the classes throughout the semester, most of them (80.8%) would remotely attend the biochemistry course again.Conclusions: Under confinement, the remote biochemistry classes were well accepted by undergraduate students of dentistry and biology programs of the Colombian public university system. The students acknowledged the quality of the classes, which significantly contributed to understanding basic concepts and motivated the students to develop a deeper comprehension of the reviewed topics. These findings suggest that combining remote learning with traditional lectures could be a suitable choice to enhance the learning process of biochemistry for students of medical and basic sciences. Undoubtedly, virtual learning is a good option for public education in the post-COVID-19 future in developing countries, such as Colombia, which generally have problems related to student desertion and failure due to economic problems.
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