Molecular phylogenetics of the bee-eaters (Aves: Meropidae) based on nuclear and mitochondrial DNA sequence data

The bee-eaters (family Meropidae) comprise a group of brightly colored, but morphologically homogeneous, birds with a wide variety of life history characteristics. A phylogeny of bee-eaters was reconstructed using nuclear and mitochondrial DNA sequence data from 23 of the 25 named bee-eater species. Analysis of the combined data set provided a well-supported phylogenetic hypothesis for the family. Nyctiornis is the sister taxon to all other bee-eaters. Within the genus Merops, we recovered two well-supported clades that can be broadly separated into two groups along geographic and ecological lines, one clade with mostly African resident species and the other clade containing a mixture of African and Asian taxa that are mostly migratory species. The clade containing resident African species can be further split into two groups along ecological lines by habitat preference into lowland forest specialists and montane forest and forest edge species. Intraspecific sampling in several of the taxa revealed moderate to high (3.7-6.5%, ND2) levels of divergence in the resident taxa, whereas the lone migratory taxon showed negligible levels of intraspecific divergence. This robust molecular phylogeny provides the phylogenetic framework for future comparative tests of hypotheses about the evolution of plumage patterns, sociality, migration, and delayed breeding strategies.     

In vitro culture and characterization of putative porcine embryonic germ cells derived from domestic breeds and Yucatan mini pig embryos at Days 20-24 of gestation

Embryonic germ cells (EGC) are cultured pluripotent cells derived from primordial germ cells (PGC). This study explored the possibility of establishing porcine EGC from domestic breeds and Yucatan mini pigs using embryos at Days 17-24 of gestation. In vitro culture of PGC from both pooled and individual embryos resulted in the successful derivation of putative EGC lines from Days 20 to 24 with high efficiency. RT-PCR showed that gene expression among all 31 obtained cell lines was very similar, and only minor changes were detected during in vitro passaging of the cells. Genome-wide RNA-Seq expression profiling showed no expression of the core pluripotency markers OCT4, SOX2, and NANOG, although most other pluripotency genes were expressed at levels comparable to those of mouse embryonic stem cells (ESC). Moreover, germ-specific genes such as BLIMP1 retained their expression. Functional annotation clustering of the gene expression pattern of the putative EGC suggests partial differentiation toward endo/mesodermal lineages. The putative EGC were able to form embryoid bodies in suspension culture and to differentiate into epithelial-like, mesenchymal-like, and neuronal-like cells. However, their injection into immunodeficient mice did not result in teratoma formation. Our results suggest that the PGC-derived cells described in this study are EGC-like, but seem to be multipotent rather than pluripotent cells. Nevertheless, the thorough characterization of these cells in this study, and especially the identification of various genes and pathways involved in pluripotency by RNA-Seq, will serve as a rich resource for further derivation of porcine EGC.     

Effects of travertine and flow on leaf retention in Fossil Creek,Arizona

Leaf retention is important in transferring energy from riparian trees to stream food webs. Retention increases with geomorphic complexity such as substrate coarseness, sinuosity, and the presence of debris dams. High discharge can reduce retention, particularly when streams lack physical trapping features. Travertine formations, caused by calcium carbonate deposition, can alter stream morphology. To date, however, we know of no study testing the effect of travertine on leaf retention. This study capitalized on a river restoration project in Fossil Creek, Arizona, where water was returned to the channel after a century of diversion. We examined how the fixed factors Flow (before and after restoration) and Morphology (travertine and riffle-pool sites) affected leaf retention. Leaf retention was higher in sites where travertine forms barriers across the river, relative to sites with riffle-pool morphology. Most leaves retained in travertine reaches were concentrated at the bottom of pools formed between dams. Although flow restoration did not alter retention rates across all sites, it diminished them at travertine sites, indicating an interaction between stream flow and morphology. We conclude that stream complexity and leaf retention are enhanced by travertine deposition but that high discharge can reduce the retentive capacity of in-stream structures. Handling editor: Darren Ryder