Defensive extrusive ectosymbionts of Euplotidium (Ciliophora) that contain microtubule-like structures are bacteria related to Verrucomicrobia

Epixenosomes, ectosymbionts on hypotrich ciliates (genus Euplotidium) defend their host against the ciliate predator Litonotus lamella. Although here only Euplotidium itoi and Euplotidium arenarium from tide pools along a rocky shore near Leghorn (Ligurian sea) were studied in detail, these epibionts are certainly present on specimens of E. itoi and on other Euplotidium species in similar north coastal habitats. The complex life history of epixenosomes has two main stages. In stage I, cells with typical prokaryotic structure divide by binary fission. Stage II cells show complex organization with different cytoplasmic compartments where an extrusive apparatus within a proteinaceous matrix, although not membrane-bounded, differs from the remaining cytoplasm. The ejection process is involved in defense; extrusive apparatus is surrounded by a basket consisting of bundles of tubules. These tubules, 22 ± 3 nm in diameter, delimited by a wall made up of globular structures, are sensitive to inhibitor of tubulin polymerization (nocodazole/4°C temperature) and react positively with different antitubulin antibodies, two of which are monoclonal. The prokaryotic vs. eukaryotic nature of epixenosomes was resolved by comparative sequence analysis of amplified small subunit rRNA genes and in situ hybridization with fluorescently labeled rRNA-targeted polynucleotide probes. These unique ectosymbionts are phylogenetically related to Verrucomicrobia. Epixenosomes represent marine symbionts in this recently discovered division of the Bacteria.

Sovereignty and Intervention in the Middle East: From the Fall of the Ottoman Empire to the Arab Spring

This research provides an institutional explanation of the practices of external intervention in the Arab state system from the fall of the Ottoman Empire in 1922 to the Arab Spring. My explanation consists of two institutional variables: sovereignty and inter-state borders. I examine the changes in regional and international norms of sovereignty and their impact on the practices of external intervention in the Arab state system. I also examine the impact of the level of institutionalization of inter-state borders in the Arab World on the practices of external intervention. I argue that changes in regional and international norms of sovereignty and changes in the level of institutionalization of inter-state borders have constituted the significant variation over time in both the frequency and type of external intervention in the Arab state system from 1922 to the present. My institutional explanation and findings seriously challenge the traditional accounts of sovereignty and intervention in the Arab World, including the cultural perspectives that emphasize the conflict between sovereignty, Arabism, and Islam, the constructivist accounts that emphasize the regional norm of pan-Arabism, the comparative politics explanations that focus on the domestic material power of the Arab state, the post-colonial perspectives that emphasize the artificiality of the Arab state, and the realist accounts that focus on great powers and the regional distribution of power in the Middle East. This research also contributes to International Relations Theory. I construct a new analytical framework to study the relations between sovereignty, borders, and intervention, combining theoretical elements from the fields of Role Theory, Social Constructivism, and Institutionalization. Methodologically, this research includes both quantitative and qualitative analysis. I conduct content analysis of official documents of Arab states and the Arab League, Arabic press documents, and Arab political thought. I also utilize quantitative data sets on international intervention.