The Myosin Heavy Chain specific A4.1025 antibody discriminates different cardiac segments in ancient groups of gnathostomes: Morphological and evolutionary implications

The pan-Myosin Heavy Chain (pan-MyHC) marker MF20 have been reported to show similar, homogeneous signal in the myocardial segments of the heart of teleosts and tetrapods. However, in an ongoing study of the myocardial structure of the dogfish (Scyliorhinus canicula; Chondrichthyes), we observed differential immunostaining of the cardiac segments using another pan-MyHC, the A4.1025 antibody. In order to investigate the relevance of this finding for better understanding of the morphology and evolution of the vertebrate heart, we performed immunohistochemistry, slot blot and western blot in several species of chondrichthyans, actinopterygians and mammals using the above mentioned antibodies. In the dogfish heart, A4.1025 and MF20 specifically recognized MyHC isoforms, although with different degree of affinity. MF20 reactivity was homogeneous and high in all the myocardial segments. However, A4.1025 reactivity was heterogeneous. It was high in the sinus venosus (external layer), atrium and atrioventricular region, low in the ventricle and conus arteriosus, and null in the internal layer of the sinus venosus. A heterogeneous pattern of A4.1025 immunoreactivity was also detected in two other elasmobranchs, a holocephalan, a polypteryform and an acipenseriform. In all of these species, MF20 immunoreactivity was homogeneous. In addition, both markers showed a homogeneous immunoreactivity pattern in teleosts and mammals. Our results indicate that in the hearts of ancient gnathostomes, in all of which a conspicuous conus arteriosus exists, one or more MyHC isoforms with low affinity for A4.1025 show segment-specific distributions. Thus, A4.1025 appears to be an appropriated marker to identify the cardiac segments and their boundaries. We propose that the segmentspecific distribution of MyHC isoforms may generate a particular type of myocardial contractility associated with the presence of a conus arteriosus.

Mapping the Liminal Experience of Eastern Europe in Selected American Works, 1965-2002

The purpose of this dissertation is to study literary representations of Eastern Europe in the works of celebrated and less-known American authors, who visited and narrated the region between the mid-1960s and early 2000s. The main critical body focuses on Eastern Europe before 1989 and encompasses three major voices of American literature: John Updike, Joyce Carol Oates, and Philip Roth. However, in the last chapter I also explore American literary perceptions of the area following the collapse of communism. Importantly, the term “Eastern Europe” as used in this dissertation is charged with significance. I approach it not only as a space on the map or the geopolitical construct which emerged in the aftermath of the Second World War, but rather as a conceptual category and a repository of meanings built out of fact and fantasy: specific historical, political and cultural realities interlaced with subjective worldviews, preconceptions, and mental images. The critical framework of this dissertation is twofold. I reach for the concept of liminality to elucidate the indeterminacy and malleability which lies at the heart of the object of study—the idea, image, and experience of Eastern Europe. Bearing in mind the nature of the works under analysis, all of which were inspired by actual visits behind the Iron Curtain, I propose to interpret these transatlantic literary journeys in terms of generative experience, where Eastern Europe is mapped as a liminal space of possibility; a contact zone between cultures and, potentially, the locus of self-discovery and individual transformation. If liminality is the metaphor or a lens that I employ in order to account for the nature of the analyzed works and the complex terrain they map, imagology, whose purpose is to study the processes of constructing selfhood and otherness in literature, provides me with the method and the critical vocabulary for analyzing selected literary representations. The dissertation is divided into six chapters, the last of which serves as coda to the previous discussion. The first two chapters constitute the critical foundation of this work. Then, in chapters 3, 4, and 5 I study American images of Eastern Europe in the works written by John Updike, Joyce Carol Oates, and Philip Roth, respectively. The last, sixth chapter of this dissertation is divided into two parts. In the first one, I discuss new critical perspectives and avenues of research in the study of Eastern Europe following the collapse of communism. Then, I carry out a joint analysis of four works written after 1989 by Eva Hoffman, Arthur Phillips, John Beckman, and Gary Shteyngart. The dissertation ends with conclusions in which I summarize my findings and reflections, and suggest implications for future research. As this dissertation seeks to demonstrate, Eastern Europe portrayed in the analyzed works oscillates between contradictory representations which are contingent upon a number of factors, most importantly who maps it and in what context. Even though each experience of Eastern Europe is distinct and fueled by the profiles, identities, and interests of the characters and their creators, I have found out that certain patterns of othering are present in all the works. Thus, my research seems to suggest that there is something of a recurrent literary image of Eastern Europe, which goes beyond the context of the Cold War. Accordingly, while this dissertation hopes to be a valid contribution to the study of literary and cultural mappings of Eastern Europe, it also generates new questions regarding the current, post-communist representation of the area and its relationship to the national tropes explored in my work.