Application of capillary electrophoresis-electrospray ionization mass spectometry in the determination of molecular diversity.

By means of capillary electrophoresis coupled online to electrospray ionization MS, a library of theoretically 171 disubstituted xanthene derivatives was analyzed. The method allowed the purity and makeup of the library to be determined: 160 of the expected compounds were found to be present, and 12 side-products were also detected in the mixture. Due to the ability of capillary electrophoresis to separate analytes on the basis of charge, most of the xanthene derivatives could be resolved by simple capillary electrophoresis-MS procedures even though 124 of the 171 theoretical compounds were isobaric with at least one other molecule in the mixture. Any remaining unresolved peaks were resolved by MS/MS experiments. The method shows promise for the analysis of small combinatorial libraries with fewer than 1000 components.

Life in the end-Permian dead zone

The fossil record of land plants is an obvious source of information on the dynamics of mass extinctions in the geological past. In conjunction with the end-Permian ecological crisis, ≈250 million years ago, palynological data from East Greenland reveal some unanticipated patterns. We document the significant time lag between terrestrial ecosystem collapse and selective extinction among characteristic Late Permian plants. Furthermore, ecological crisis resulted in an initial increase in plant diversity, instead of a decrease. Paradoxically, these floral patterns correspond to a “dead zone” in the end-Permian faunal record, characterized by a paucity of marine invertebrate megafossils. The time-delayed, end-Permian plant extinctions resemble modeled “extinction debt” responses of multispecies metapopulations to progressive habitat destruction.