Heterocyst glycolipid synthase (HglT) catalyzes the final step of heterocyst glycolipid (Hgl) biosynthesis, in which a glucose is transferred to the aglycone (fatty alcohol). Here we describe the isolation of hglT null mutants. These mutants lacked Hgls under nitrogen-starved conditions and instead accumulated fatty alcohols. Differentiated heterocyst cells in the mutants were morphologically indistinguishable from those of the wild-type cells. Interestingly, the mutants grew under nitrogen starvation but fixed nitrogen with lower nitrogenase activity than did the wild-type. The mutants had a pale green phenotype with a decreased chlorophyll content, especially under nitrogen-starved conditions. These results suggest that the glucose moiety of the Hgls may be necessary for optimal protection against oxygen influx but is not essential and that aglycones can function as barriers against oxygen influx in the heterocyst cells.
In chemistry, laboratory works are ideal media for students to understand the connection between the unseen microscopic world and the observable macroscopic world. Laboratory experiences provide opportunities for team building, inquiry-based learning, hands-on activities, and exposure to standard laboratory equipment and technology. Many of the concepts and principles common in high school chemistry courses can actually be demonstrated or discovered through experiments performed with simple apparatus. Currently, investigations on the Indonesian teachers' performance in designing practical chemistry laboratory are still very rare. The investigation is crucial to understand the problems and challenges faced by Chemistry teachers in preparing laboratory works and to improve their performance based on the research findings. This study investigated the teachers' current practice of laboratory activities in various high schools in West Java, Indonesia. This research is a survey research with a qualitative approach. The research subjects were 27 senior high school. The instrument used in this study was a non-test in the form of a Likert scale questionnaire. The questionnaires consisted of 9 items covering the pre-laboratory activity, during laboratory activity and postlaboratory activity. It was found that the number of experiments conducted, teachers' preparation and the reflection session after laboratory works were considered sufficient. However, the teachers' awareness on the safety instruction and green chemistry approach were still low. Additionally, laboratory works that focuses on the problem-based and discovery are not popular among teachers. It is suggested that the later practical work method is introduced to teachers because this approach allows students to practice higher level analytical skills, problem solving, connection to theory and transferable skills.
This research aims to indentify the views of pre-service chemistry teachers about the nature of science and technology. This research was conducted using descriptive methods with participants consisting of 28 students of the Universitas Lampung. Data was collected using a view of the nature of science and technology (VNOST) questionnaire consisting of 4 aspects: Definition of science and technology, Epistemology of science, Sociology of Internal science, and external sociology of science. The results of this study indicate that pre-service teachers define science as a concept and technology as a science application. In the epistemology of science, they view scientific models as genuine objects and there are many ways to calcify. In internal science sociology, scientific decisions are based on previous theories and technological decisions based on their impact on society. For external sociology of science, pre-service teachers who agree with science-technology-society influence and influence each other. In general, the results also revealed that most of them had a good view. The results of this research will be made didactic design in the context of ionic liquids as cellulose solvents to improve the ability of VNOST pre-service chemistry teacher.
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