Escherichia coli possesses a soluble flavohemoglobin, with an unknown function, encoded by the hmp gene. A monolysogen containing an hmp-lacZ operon fusion was constructed to determine how the hmp promoter is regulated in response to heme ligands (O2, NO) or the presence of anaerobically utilized electron acceptors (nitrate, nitrite). Expression of the phi (hmp-lacZ)1 fusion was similar during aerobic growth in minimal medium containing glucose, glycerol, maltose, or sorbitol as a carbon source. Mutations in cya (encoding adenylate cyclase) or changes in medium pH between 5 and 9 were without effect on aerobic expression. Levels of aerobic and anaerobic expression in glucose-containing minimal media were similar; both were unaffected by an arcA mutation. Anaerobic, but not aerobic, expression of phi (hmp-lacZ)1 was stimulated three- to four-fold by an fnr mutation; an apparent Fnr-binding site is present in the hmp promoter. Iron depletion of rich broth medium by the chelator 2'2'-dipyridyl (0.1 mM) enhanced hmp expression 40-fold under anaerobic conditions, tentatively attributed to effects on Fnr. At a higher chelator concentration (0.4 mM), hmp expression was also stimulated aerobically. Anaerobic expression was stimulated 6-fold by the presence of nitrate and 25-fold by the presence of nitrite. Induction by nitrate or nitrite was unaffected by narL and/or narP mutations, demonstrating regulation of hmp by these ions via mechanisms alternative to those implicated in the regulation of other respiratory genes. Nitric oxide (10 to 20 microM) stimulated aerobic phi (hmp-lacZ)1 activity by up to 19-fold; soxS and soxR mutations only slightly reduced the NO effect. We conclude that hmp expression is negatively regulated by Fnr under anaerobic conditions and that additional regulatory mechanisms are involved in the responses to oxygen, nitrogen compounds, and iron availability. Hmp is implicated in reactions with small nitrogen compounds.

It is becoming increasingly clear that not all students require the same education, and the requirement of personalized education is increasingly in demand. The incorporation of adaptive learning (AL) has increased in recent years. However, research on this subject is still evolving at the university level. In this study, we investigated the impact of integrating an AL tool (CogBooks®) in a university course (statistics for decision making) taught in an innovative online modality called FIT (flexible, interactive, and with technology), in which the course is designed in the CANVAS® platform and uses Zoom® as a means of communication with students. Learning outcomes were compared between the FIT courses with or without AL and between AL strategies in online and face-to-face courses. It was clear that AL improved the students’ achievement regardless of the modality. In addition, we conclude that students achieve better in AL courses in the classroom than in distance courses. Satisfaction surveys favor a preference for FIT courses with AL over classroom classes with AL. Our results suggest that AL is a solid strategy for teaching undergraduate courses. Graphical abstract

Escherichia coli possesses a flavohemoglobin (Hmp), product of hmp, the first microbial globin gene to be sequenced and characterized at the molecular level. Although related proteins occur in numerous prokaryotes and eukaryotic microorganisms, the function(s) of these proteins have been elusive. Here we report construction of a defined hmp mutation and its use to probe Hmp function. As anticipated from up-regulation ofhmp expression by nitric oxide (NO),S-nitrosoglutathione (GSNO) or sodium nitroprusside (SNP), the hmp mutant is hypersensitive to these agents. Thehmp promoter is more sensitive to SNP andS-nitroso-N-penicillamine (SNAP) than is thesoxS promoter, consistent with the role of Hmp in protection from reactive nitrogen species. Additional functions for Hmp are indicated by (a) parallel sensitivity of thehmp mutant to the redox-cycling agent, paraquat, (b) inability of the mutant to up-regulate fully thesoxS and sodA promoters in response to oxidative stress caused by paraquat, GSNO and SNP, and (c) failure of the mutant to accumulate reduced paraquat radical after anoxic growth. We conclude that Hmp plays a role in protection from nitrosating agents and NO-related species and oxidative stress. This protective role probably involves direct detoxification of those species and sensing of NO-related and oxidative stress.