Browsing by Subject "Azolla"

Science has an inspiring capacity to change the world around us as it informs of the details governing life. From feats of engineering to medical breakthroughs, it has rapidly changed the way we live. Though it is woven into the fabric of all we do, there are still gaps between science and society—such as how science is shared from the academy and connects to communities. This has always fascinated me and the resulting body of this dissertation is three parts biology, exploring the symbiosis between the small aquatic fern, Azolla, and its cyanobacterial symbiont, Nostoc azollae; and one-part sociology, examining ways to reconnect science to the society it impacts so deeply and to which it owes so much. My hope is that within these pages you will find a new enthusiasm for plants—especially the tiny wonder, Azolla—and that you will see the value I do in strengthening the connection between science and the communities around it. With everything we do as scientists we have the power to affect the world around us, and it is our responsibility to think deeply about how we engage and join science and society together for the betterment of us all.

Chapters 2 and 3 focus on the biological aspects of the symbiosis between the aquatic fern, Azolla filiculoides, and its symbiont, N. azollae. It is not so coincidental that this symbiosis ended up being the subject of my research and has sweeping connections to societies around the globe—including its use as a green fertilizer in China for over 1500 years. Azolla is a small genus of aquatic fern with immense green potential to positively impact the globe. It owes this distinction to the nitrogen-fixing cyanobacterial symbiont, N. azollae, it harbors within specialized cavities within its photosynthetic leaves. These two partners have been living together for over 90 million years. There are many plant microbial symbioses, however, what makes the Azolla-Nostoc symbiosis unique among the others is that the cyanobiont is intimately associated with the fern perpetually throughout both organisms’ life cycles. The two are rarely—if ever—seen apart. This symbiosis has long captured the curiosity of scientists, who have explored various aspects in detail, such as what compounds are exchanged between the two partners, how the leaf cavities develop, and what structures are present within the cavities. Presently, we are at a stage to delve deeply into understanding the way this symbiosis thrives by exploring the genome, transcriptome, and connecting these to features of the leaf cavity.

Chapter 2 details a visual examination of the symbiosis using confocal microscopy. I used a clearing protocol coupled with confocal microscopy to image the leaves of Azolla filiculoides as the symbiosis develops to visualize the symbiotic cavity and labeled different cellular components with the fluorescent dyes calcofluor white and 4’,6-diamidino-phenylindole (DAPI). I imaged the cavity trichomes within the leaf pocket in whole leaves, as well as the trichomes at the apex that facilitate movement of the cyanobiont into the megaspores. These trichomes are the main plant structures that interact with the cyanobiont. The ultimate goal is to use this technique alongside the genomics and transcriptomics data (chapters 3 and 4) to identify the functions of the trichomes, eventually outlining the strategy A. filiculoides uses to engage in its symbiosis.

Chapter 3 takes a closer look at the putative symbiosis genes. I examined the expression of ammonium assimilation genes and their potential post-translational modifications; as well as how the larger pool of putative symbiosis genes may be transcriptionally regulated and what their functional categories are using gene ontology analysis. The RNA-sequencing analysis revealed 160 putative symbiosis genes. These genes included nutrient transporters for compounds like ammonium and molybdate, but did not include glutamine synthetase, glutamate synthase genes, or sucrose transporters. We also found that the nitrogen assimilation genes in A. filiculoides lack the post-translational modifications used in other plants to regulate their activity, leading to questions about how Azolla does this differently. This work provides the groundwork for establishing new ideas for how the Azolla-Nostoc symbiosis works, which factors are used to communicate between the two partners and what is used to regulate the exchange of nutrients, all of which allows their life cycles to be linked together.

This dissertation concludes with a departure from the biology of the Azolla-Nostoc symbiosis, and transitions into a survey of how science and society can be reconnected. In chapter 4, I detail three case studies addressing problems that keep science and society separated— (1) the inaccessibility of science to certain groups, (2) the inability of scientists to build trusting relationships with non-scientific audiences, and (3) the lack of innovative ways to engage the public about science. The first case study specifies programs I have been involved in to engage underrepresented minority students in the sciences. I also detail work to improve science to make it an inclusive environment for these students to succeed and thrive. The second case study focuses on training and preparing scientists to interact with the public. This is crucial to share science in ways that are accessible and resonate with people. I remark on my use of improvisational comedy as a way of making scientists more attentive to their audiences as they are presenting as well as improving their own body awareness. I also discuss work to introduce them to the basics of good science communication, and outreach opportunities to put this training into practice. In the third case study, I make a case for joining the arts and sciences as a means to powerfully connect science and people. This comes from a science and art exhibit that I launched with fellow graduate students, that has sparked a wave of other science-art minded endeavors. The combination of art, science, and community-engagement hit upon a way to captivate the public and pull them into the stories behind science. Together, these seek to be examples of how we can rejoin science and society in meaningful ways, allowing all people to share in science and see how science weaves into our lives.