TESTS FOR ANCIENT SPECIES FLOCKS BASED ON MOLECULAR PHYLOGENETIC APPRAISALS OF SEBASTES ROCKFISHES AND OTHER MARINE FISHES

The concept of species flocks has been central to previous interpretations of patterns and processes of explosive species radiations within several groups of freshwater fishes. Here, molecular phytogenies of species-rich Sebastes rockfishes from the northeastern Pacific Ocean were used to test predictions of null theoretical models that assume random temporal placements of phylogenetic nodes. Similar appraisals were conducted using molecular data previously published for particular cichlid fishes in Africa that epitomize, by virtue of a rapid and recent radiation of species, the traditional concept of an intralacustrine “species flock.” As gauged by the magnitudes of genetic divergence in cytochrome b sequences from mitochondrial DNA, as well as in allozymes, most speciation events in the Sebastes complex were far more ancient than those in the cichlids. However, statistical tests of the nodal placements in the Sebastes phylogeny suggest that speciation events in the rockfishes were temporally nonrandom, with significant clustering of cladogenetic events in time. Similar conclusions also apply to an ancient complex of icefishes (within the Notothenioidei) analyzed in the same fashion. Thus, the rockfishes (and icefishes) may be interpreted as ancient species flocks in the marine realm. The analyses exemplified in this report introduce a conceptual and operational approach for extending the concept of species flocks to additional environmental settings and evolutionary timescales.     

Partially dephosphorylated phosphopeptide AcSer(P)-Ser(P)-Ser(P) is an excellent substrate for casein kinase-2

The synthetic phosphopeptide AcSer(P)-Ser(P)-Ser(P), reproducing a recurrent feature of casein and other phosphoproteins, once partially dephosphorylated by acid phosphatase, serves as an efficient substrate for casein kinase-2. Previous dephosphorylation beyond 30% hinders subsequent phosphorylation and the entirely dephosphorylated peptide is not a substrate at all. The kinetic constants of the partially dephosphorylated phosphopeptide are much more favourable than those of the synthetic peptides SEEEAA, SSEE and SEE, the latter one being totally inert. Optimal phosphorylation occurs at pH values that ensure complete ionization of the phosphoseryl side chains. These data provide incontrovertible demonstration that phosphoserine can replace carboxylic amino acids as specificity determinant for CK-2, being more effective than glutamic acid itself.     

Glycoalkaloids of Solanum Series Megistacrolobum and related potato cultigens

Glycoalkaloids were used as evidence of the affinities of nine taxa of Solanum Series Megistacrolobum and related potato cultigens from western Bolivia. S. boliviense, S. sanctae-rosae and S. toralapanum contain the commertetraose sugar moiety and appear to represent a relatively wild group within the Series. S. megistacrolobum, S. sogarandinum and S. raphanifolium show anomolous glycoalkaloid profiles that probably reflect hybridization associated with human disturbance. Primitive forms of the S. χ ajanhuiri cultigen are indistinguishable chemicaliy from conspecific weeds that were previously classified as S. megistacrolobum. Variation in total glycoalkaloid content within Series Megistacrolobum likely reflects direct selection by humans for reduced glycoalkaloid levels during the domestication process.