Phylogeographic history of the New Zealand stick insect Niveaphasma annulata (Phasmatodea) estimated from mitochondrial and nuclear loci.

We have assessed the utility of a single-copy nuclear locus and mitochondrial DNA (mtDNA) in a phylogeographic study of the New Zealand stick insect Niveaphasma annulata (Hutton). We amplified sequences from the mitochondrial cytochrome oxidase subunit I (COI) gene and the single-copy nuclear gene elongation factor-1alpha (EF1alpha) from 97 individuals. Allelic phase at the EF1alpha locus was determined using Denaturing Gradient Gel Electrophoresis. Phylogenetic analyses showed broad congruence between the geographic distribution of three major COI clades and EF1alpha alleles, which suggested that the phylogenetic patterns reflect population history rather than lineage sorting. However, the geographic boundaries of these clades were not always in exact agreement between the two loci. Our data indicate that Niveaphasma annulata was most likely separated into a number of refugia during Pleistocene glacial advances. Subsequent to glacial retreat these refugial populations have expanded and now form a number of zones of secondary contact. We contrast these patterns with those observed from other New Zealand taxa. Our study offers compelling evidence for the use of nuclear genes alongside mtDNA for future phylogeographic studies.

Phylogeography of two New Zealand lizards: McCann's skink (Oligosoma maccanni) and the brown skink (O. zelandicum).

The New Zealand skink fauna has proven to be an ideal taxonomic group in which to examine the impact of climatic and geological processes on the evolution of the New Zealand biota since the Pliocene. Here we examine the phylogeography of McCann's skink (Oligosoma maccanni) in order to gain insight into the relative contribution of Pliocene and Pleistocene processes on patterns of genetic structure in the South Island biota, and investigate the phylogeography of the brown skink (O. zelandicum) to examine whether Cook Strait landbridges facilitated geneflow between the North and South Islands in the late-Pleistocene. We obtained mitochondrial DNA sequence data (ND2 and ND4; 1282bp) from across the range of both species. We examined the phylogeographic patterns evident in each species using Neighbour-Joining, Maximum Likelihood and Bayesian methods. We found substantial phylogeographic structure within O. maccanni, with seven distinct clades identified. Divergences among clades are estimated to have occurred during the Pliocene. Populations in the Otago/Southland region (south of the Waitaki River valley) formed a well-supported lineage within O. maccanni. A substantial genetic break was evident between populations in east and west Otago, either side of the Nevis-Cardrona fault system, while north-south genetic breaks were evident within the Canterbury region. Within-clade divergences in O. maccanni appear to have occurred during the mid- to late-Pleistocene. Shimodaira-Hasegawa topology tests indicated that the 'Garston' skink is not genetically distinct from O. maccanni. There was only relatively minor phylogeographic structure within O. zelandicum, with divergences among populations occurring during the mid- to late-Pleistocene. Our genetic data supports a single colonisation of the North Island by O. zelandicum from the South Island, with the estimated timing of this event (0.46mya) consistent with the initial formation of Cook Strait.

Targeting Cx43 and N-cadherin, which are abnormally upregulated in venous leg ulcers, influences migration, adhesion and activation of Rho GTPases.

BACKGROUND: Venous leg ulcers can be very hard to heal and represent a significant medical need with no effective therapeutic treatment currently available. PRINCIPAL FINDINGS: In wound edge biopsies from human venous leg ulcers we found a striking upregulation of dermal N-cadherin, Zonula Occludens-1 and the gap junction protein Connexin43 (Cx43) compared to intact skin, and in stark contrast to the down-regulation of Cx43 expression seen in acute, healing wounds. We targeted the expression of these proteins in 3T3 fibroblasts to evaluate their role in venous leg ulcers healing. Knockdown of Cx43 and N-cadherin, but not Zonula Occludens-1, accelerated cell migration in a scratch wound-healing assay. Reducing Cx43 increased Golgi reorientation, whilst decreasing cell adhesion and proliferation. Furthermore, Connexin43 and N-cadherin knockdown led to profound effects on fibroblast cytoskeletal dynamics after scratch-wounding. The cells exhibited longer lamelipodial protrusions lacking the F-actin belt seen at the leading edge in wounded control cells. This phenotype was accompanied by augmented activation of Rac-1 and RhoA GTPases, as revealed by Förster Resonance Energy Transfer and pull down experiments. CONCLUSIONS: Cx43 and N-cadherin are potential therapeutic targets in the promotion of healing of venous leg ulcers, by acting at least in part through distinct contributions of cell adhesion, migration, proliferation and cytoskeletal dynamics.