Interactive cloning with the SH3 domain of N-src identifies a new brain specific ion channel protein, with homology to Eag and cyclic nucleotide-gated channels

We have isolated a novel cDNA, that appears to represent a new class of ion channels, by using the yeast two-hybrid system and the SH3 domain of the neural form of Src (N-src) as a bait. The encoded polypeptide, BCNG-1, is distantly related to cyclic nucleotide-gated channels and the voltage-gated channels, Eag and H-erg. BCNG-1 is expressed exclusively in the brain, as a glycosylated protein of ≈132 kDa. Immunohistochemical analysis indicates that BCNG-1 is preferentially expressed in specific subsets of neurons in the neocortex, hippocampus, and cerebellum, in particular pyramidal neurons and basket cells. Within individual neurons, the BCNG-1 protein is localized to either the dendrites or the axon terminals depending on the cell type. Southern blot analysis shows that several other BCNG-related sequences are present in the mouse genome, indicating the emergence of an entire subfamily of ion channel coding genes. These findings suggest the existence of a new type of ion channel, which is potentially able to modulate membrane excitability in the brain and could respond to regulation by cyclic nucleotides.

A new extinct primate among the Pleistocene megafauna of Bahia, Brazil.

A nearly complete skeleton of a robust-bodied New World monkey that resembles living spider monkeys was recovered from undisturbed Pleistocene deposits in the Brazilian state of Bahia. The skeleton displays the highly specialized postcranial pattern typical of spider and woolly spider monkeys and shares cranial similarities to the spider monkey exclusively. It is generically distinct on the basis of its robustness (>20 kg) and on the shape of its braincase. This new genus indicates that New World monkeys nearly twice the size of those living today were part of the mammalian biomass of southern Amazonia in the late Pleistocene. The discovery of this specimen expands the known adaptive diversity of New World monkeys and demonstrates that they underwent body size expansion in the terminal Pleistocene, as did many other types of mammals.

Flightless brown kiwis of New Zealand possess extremely subdivided population structure and cryptic species like small mammals.

Using allozymes and mtDNA sequences from the cytochrome b gene, we report that the brown kiwi has the highest levels of genetic structuring observed in birds. Moreover, the mtDNA sequences are, with two minor exceptions, diagnostic genetic markers for each population investigated, even though they are among the more slowly evolving coding regions in this genome. A major unexpected finding was the concordant split in molecular phylogenies between brown kiwis in the southern South Island and elsewhere in New Zealand. This basic phylogeographic boundary halfway down the South Island coincides with a fixed allele difference in the Hb nuclear locus and strongly suggests that two morphologically cryptic species are currently merged under one polytypic species. This is another striking example of how molecular genetic assays can detect phylogenetic discontinuities that are not reflected in traditional morphologically based taxonomies. However, reanalysis of the morphological characters by using phylogenetic methods revealed that the reason for this discordance is that most are primitive and thus are phylogenetically uninformative. Shared-derived morphological characters support the same relationships evident in the molecular phylogenies and, in concert with the molecular data, suggest that as brown kiwis colonized northward from the southern South Island, they retained many primitive characters that confounded earlier systematists. Strong subdivided population structure and cryptic species in brown kiwis seem to have evolved relatively recently as a consequence of Pleistocene range disjunctions, low dispersal power, and genetic drift in small populations.