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Obsidian was an important resource throughout Mesoamerica, and found at nearly all sites. Sources of obsidian were located in the Mexican Highlands and Guatemalan Highlands, often being transported over hundreds of kilometers for distribution. In this paper I chose four Maya sites-El Ceibal, Tikal, Xtobo, and Actun Uayazba Kab-and used three obsidian distribution models previously published by De León et al. in 2009, to infer possible distribution methods used in the Maya Lowlands. Though limitations existed the results from this proof-of-concept analysis indicate that distribution models derived for central Mexican contexts are suitable for Maya regions, and that the Maya were engaged in multiple forms of blade trade.

Site-specific photomodification of the 5'-terminal fragment of MDR1 mRNA by perfluoroarylazide derivatives of 2'-O-modified (2'-O-methyl or 2'-O-tetrahydropyranyl) oligoribo- and oligodeoxyribonucleotides was investigated. The conjugates built of 2'-O-modified oligoribonucleotides demonstrate beneficial features compared with their deoxyribo analogs: the extent of RNA modification by 2'-O-modified oligoribonucleotides and oligodeoxyribonucleotide conjugates was 40- 50% and 20%, respectively.