The inducible Mar phenotype of Escherichia coli is associated with increased tolerance to multiple hydrophobic antibiotics as well as some highly hydrophobic organic solvents such as cyclohexane, mediated mainly through the AcrAB/TolC efflux system. The influence of water miscible alcohols ethanol and 1-propanol on a Mar constitutive mutant and a mar deletion mutant of E. coli K-12, as well as the corresponding strains carrying the additional acrAB deletion, was investigated. In contrast to hydrophobic solvents, all strains were killed in exponential phase by 1-propanol and ethanol at rates comparable to the parent strain. Thus, the Mar phenotype does not protect E. coli from killing by these more polar solvents. Surprisingly, AcrAB does not contribute to an increased alcohol tolerance. In addition, sodium salicylate, at concentrations known to induce the mar operon, was unable to increase 1-propanol or ethanol tolerance. Rather, the toxicity of both solvents was increased in the presence of sodium salicylate. Collectively, the results imply that the resilience of E. coli to water miscible alcohols, in contrast to more hydrophobic solvents, does not depend upon the AcrAB/TolC efflux system, and suggests a lower limit for substrate molecular size and functionality. Implications for the application of microbiological systems in environments containing high contents of water miscible organic solvents, e.g.,phage display screening, are discussed.

Teaching and learning in science disciplines are dependent on multimodal communication. Earlier research implies that students may be challenged when trying to interpret and use different semiotic resources. There have been calls for extensive frameworks that enable analysis of multimodal texts in science education. In this study, we combine analytical tools deriving from social semiotics, including systemic functional linguistics (SFL), where the ideational, interpersonal, and textual metafunctions are central. In regard to other modes than writing—and to analyse how textual resources are combined—we build on aspects highlighted in research on multimodality. The aim of this study is to uncover how such a framework can provide researchers and teachers with insights into the ways in which various aspects of the content in multimodal texts are communicated through different semiotic resources. Furthermore, we aim to explore how different text resources interact and, finally, how the students, or authors of teaching resources, position themselves in relation to the subject. Data consist of one student text and one teaching resource text, both comprising drawn and written elements in combination with symbols. Our analyses of the student text suggest that the proposed framework can provide insights into students’ content knowledge and, hence, how construction of multimodal texts may be a useful tool for formative assessment. When it comes to teaching resources, the framework may be a useful tool for teachers when choosing resources, particularly in relation to students’ possibilities of meaning making when engaging with such texts, but also, as a basis for classroom discussions.

Since visual representations play a particularly important role in the teaching and learning of chemistry, the exploration described in this article focuses on them. This is an explorative study of the qualitatively different ways that visual representations can be unpacked by Swedish upper secondary school chemistry teachers dealing with intermolecular forces. Unpacking is characterized as the ways that visual representations get used to open up the possibility of having the critical aspects and features of an intended object of learning being brought into focal awareness, initially on their own and then simultaneously. The analysis, which combines a phenomenographic and a social semiotic approach, leads to the characterizations of five qualitatively different ways that visual representations may be unpacked. These outcome categories are presented in terms of a conceptual hierarchy, where two of these ways of unpacking are characterized as being teacher‐centered and the other three as student‐centered. This leads to a case being made that if teachers use student‐centered ways of unpacking visual representations, then their students will be more likely to gain greater access to critical aspects and features of the enacted object of learning. We argue that in terms of making theoretical and practical contributions to the phenomenographic perspective on learning, the results can be used as a tool for researchers wishing to explore how visual representations can be used effectively in science education and also provide a useful basis for discussion in teacher education and in teacher professional development programs.

Teaching and learning in ecology depend on multimodality, involving semiotic resources such as visual representations, subject-specific symbols, and written and spoken language. Furthermore, the ecology field involves complex processes and relationships, presenting student challenges. However, more research has yet to investigate how students design multimodal texts to represent complex biological processes. For a holistic understanding of ecology, it is crucial to understand different complex processes, such as the matter cycle, energy flow, decomposition, and their relations. Therefore, this study aims to, through multimodal text analysis based on systemic functional linguistics (SFL), identify how secondary students collectively present and combine such processes and how they position themselves through their textual choices. Results indicate that representing biological processes comprises several challenges for students. One way in which this is shown is the unclear use and meaning of arrows. Thereto, the students include various aspects uncommon in the field of ecology, for example, symbols inspired by comic books, values, and the role of humans, thereby relating ecosystems to their interests and everyday life. Implications for teaching are discussed, for instance, the importance of supporting students in terms of scientific content and how to represent it, which can be conducted through text discussions.

Genetics and organic chemistry are areas of science that students regard as difficult to learn. Part of this difficulty is derived from the disciplines having representations as part of their discourses. In order to optimally support students’ meaning-making, teachers need to use representations to structure the meaning-making experience in thoughtful ways that consider the variation in students’ prior knowledge. Using a focus group setting, we explored 43 university students’ reasoning on representations in introductory chemistry and genetics courses. Our analysis of eight focus group discussions revealed how students can construct somewhat bewildered relations with disciplinary-specific representations. The students stated that they preferred familiar representations, but without asserting the meaning-making affordances of those representations. Also, the students were highly aware of the affordances of certain representations, but nonetheless chose not to use those representations in their problem solving. We suggest that an effective representation is one that, to some degree, is familiar to the students, but at the same time is challenging and not too closely related to “the usual one”. The focus group discussions led the students to become more aware of their own and others ways of interpreting different representations. Furthermore, feedback from the students’ focus group discussions enhanced the teachers’ awareness of the students’ prior knowledge and limitations in students’ representational literacy. Consequently, we posit that a focus group setting can be used in a university context to promote both student meaning-making and teacher professional development in a fruitful way.

This is the third article in a series, emanating from a project that used social semiotics and phenomenography to explore the role visual representations play in the teaching and learning of chemistry. Building on our earlier work that identified five qualitatively different ways that teachers may use to unpack visual representations in their introductory classes at upper secondary school when dealing with intermolecular forces, this article deals with how students describe their experience of chemistry teachers’ unpacking of visual representations. The theoretical thematic analysis, grounded in phenomenography and social semiotics, foregrounds qualitative differences in students’ experiences of teachers’ representational work. The results show that the ways of unpacking that we previously characterized as student‐centered were described by the students as being particularly valuable. Here, a key point from a student perspective is that the teacher reflects on how to verbally guide them through the unpacking process in ways that support them in their meaning‐making. We use these results to propose that chemistry teacher practice and education can be modified to emphasize the importance of seeing the practice of unpacking from a semiotic perspective. Furthermore, based on our findings and previous research in the chemistry education field, we conclude by suggesting a strategy that can be used in teacher education and by in‐service teachers as a basis for planning chemistry lessons and reflecting on them, particularly with respect to the visual representations employed.