Don't use journal article graphics in a slide presentation
It is not uncommon for scientific presentations to include graphics that have been prepared for journal articles. Don't do this! A graphic for a journal article serves a very different purpose than an effective visual for a slide presentation.
Figures in biomedical research journals typically contain multiple graphs, abbreviations, and a great deal of complexity. Axes are in small font and often written in a vertical format. This can be acceptable, even desirable, in a journal article because there is the opportunity for the author to explain each graph and the reader can take the time to reread the article and study the figures in depth. In a journal article the audience (the reader) sets the pace for learning.
The opposite is true in a slide presentation. The speaker sets the pace for learning and the audience suffers with inappropriate tempo. When a new slide appears the audience does not know what part of the slide to focus on. Those multi-graph slides derived from journal articles add to the confusion.
Every slide in a presentation needs to have one overarching message and the data should support that message. Extra graphs that the speaker does not discuss only confuse the audience.
Remember, "talk about what you show, show what you talk about." If you don't talk about it, why is it on the slide? Take the time to edit those journal article figures so that they are appropriate for a slide presentation.