Observation of Living Organisms in Environmental Samples by Transmission-Through-Dye Microscopy

Abstract

Transmission-through-dye (TTD) microscopy renders live cells bright red over a dark background. Previously TTD had been used for cell volume measurements; in this article the strong contrast generated by TTD is presented as a stand-alone merit, in particular for observation of environmental samples. Such samples often contain large amounts of detritus that can easily obscure living cells and organisms. TTD imaging allows the microscopist to circumvent this difficulty: cells with intact membranes turn bright on TTD images, whereas dead matter remains dark. This property of TTD can be valuable for observing and studying aquatic life.

Assessing the Effectiveness of a Novel Microscopy Technique in Middle & High School Science Classrooms

“…TTD adds strong contrast to transparent cells, making them easily visible and distinct from dead matter and debris (see Figure 2; Gregg et al, 2010). This property of the technique can be utilized for studying aquatic microorganisms (Model & Davis, 2016). In this mixed-methods research study, we set out to determine whether a three-week inquiry-based unit focused on TTD microscopy resulted in differences in middle school students' content test scores, as well as their conceptual understandings of microscopy techniques and microorganisms.…”

Methods for cell volume measurement

“…The dye exclusion method has been applied to mammalian living cells , formaldehyde‐fixed cells , bacteria . and protists . The method cannot be used for absolute volume measurements on confluent cultures, where the background intensity is unavailable.…”