Niels Bonderup Dohn

Bicarbonate binding to hemoglobin links oxygen and carbon dioxide transport in hagfish.

Hagfish are unusual among vertebrates in having red cells that almost completely lack the anion-exchanger membrane protein band III and hemoglobins that are highly sensitive to CO2 but only weakly affected by protons. This suggests a different linkage between oxygen and CO2 transport from that of the majority of vertebrates, which is characterized by oxygen-linked proton binding to hemoglobin and chloride-bicarbonate exchange across band III protein. We here report that the hemoglobin of the hagfish Myxtne glutinosa shows oxygen-linked binding of bicarbonate, which decreases the oxygen affinity and thereby enhances oxygen unloading to the tissues. Bicarbonate binding to the hemoglobin moreover facilitates the hydration of CO2 and its transport as intraerythrocytic bicarbonate, and may compensate at least in part for the virtual absence of band III protein. This represents a unique linkage between oxygen and CO2 transport among vertebrates, where the physiological role of protons in the Bohr and Haldane effects is played by bicarbonate ions.

Volume Regulation in Red Blood Cells

Hagfish erythrocytes lack the anion exchanger (band 3 protein) in their membranes. This protein has been suggested to play a key role in the activation of a regulatory volume decrease in teleost and elasmobranch fishes. A total lack of the ability of cellular volume regulation in hagfish erythrocytes supports this notion. The lack of volume regulation is accompanied by an extreme stability of hagfish erythrocytes when exposed to aniso-tonic media.

The role of teacher questions in the chemistry classroom

The purpose of this study was to investigate how a chemistry teachers questions influence the classroom discourse. It presents a fine-grained analysis of the rich variety of one teachers questions and the roles they play in an upper secondary chemistry classroom. The study identifies six different functions for the teachers questions: Student Knowledge, Request, Monologic Discourse, Clarification, Relations and Interaction of Contexts. Overall, these questions create a safe and interactive learning environment. However, the questions are predominantly closed in form. As a result, the students become highly accomplished in recalling facts but have difficulties when higher order thinking is required. The findings suggest that an interactive classroom can be created by using many engaging teacher questions. The six different categories of questions promote the students’ learning process as it gives them authority and entitles them to speak and learn.

Interest and Emotions in Science Education

Interest is an important affective variable that has been found to be associated with focused attention, higher cognitive functioning, and learning, which makes it important for learning science. In research on interest and learning, this interplay is almost always seen in a unidirectional way where interest is a facilitator of learning. The aim of this chapter is to challenge this unidirectional view on the role of interest – with special emphasis on feelings – in learning science. We do this by reversing the direction and investigating if learning science can be a facilitator for developing interest. We start with a theoretical outline of interest and feelings connected to this. This will be put into the context of students’ work in upper secondary biology education for an empirical approach to this interplay. The empirical work will provide arguments for the theoretical outline but also qualify the final discussion on the role of interest and the attached emotions, feelings, and moods in science education in general at a theoretical and practical level and how these correspond with leaning science.