Genome-wide RAD sequencing resolves the evolutionary history of serrate leaf Juniperus and reveals discordance with chloroplast phylogeny

Juniper (Juniperus) is an ecologically important conifer genus of the Northern Hemisphere, the members of which are often foundational tree species of arid regions. The serrate leaf margin clade is native to topologically variable regions in North America, where hybridization has likely played a prominent role in their diversification. Here we use a reduced-representation sequencing approach (ddRADseq) to generate a phylogenomic data set for 68 accessions representing all 22 species in the serrate leaf margin clade, as well as a number of close and distant relatives, to improve understanding of diversification in this group. Phylogenetic analyses using three methods (SVDquartets, maximum likelihood, and Bayesian) yielded highly congruent and well-resolved topologies. These phylogenies provided improved resolution relative to past analyses based on Sanger sequencing of nuclear and chloroplast DNA, and were largely consistent with taxonomic expectations based on geography and morphology. Calibration of a Bayesian phylogeny with fossil evidence produced divergence time estimates for the clade consistent with a late Oligocene origin in North America, followed by a period of elevated diversification between 12 and 5 Mya. Comparison of the ddRADseq phylogenies with a phylogeny based on Sanger-sequenced chloroplast DNA revealed five instances of pronounced discordance, illustrating the potential for chloroplast introgression, chloroplast transfer, or incomplete lineage sorting to influence organellar phylogeny. Our results improve understanding of the pattern and tempo of diversification in Juniperus, and highlight the utility of reduced-representation sequencing for resolving phylogenetic relationships in non-model organisms with reticulation and recent divergence

Effect of glycine and glycine receptor antagonists on NMDA-induced brain injury

In postnatal day 7 rats, a unilateral intrastriatal injection of 12.5 nmol of (NMDA) reproducibly injures the ipsilateral striatum, adjacent hippocampus and overlying cortex. The severity of injury can be quantified by comparing cerebral hemisphere weights in animals sacrificed 5 days after the injection. Co-injection of NMDA and the glycine receptor antagonists kynurenic acid (KYN) or 7-chlorokynurenic acid (7-CKA) reduced the severity of NMDA-induced damage in a dose-dependent fashion. One hundred nmol of KYN with 12.5 nmol of NMDA reduced average % damage from 19.3+/-0.9% (n=9) to 2.3+/-0.5% (n=6), Pn=6) reduced average % damage from 17.1+/-1.6% (n=15) to 3.0+/-0.6%, P<0.001, ANOVA. Concurrent injection of 1000 nmol glycine with 5 nmol NMDA did not increase the extent of NMDA-induced damage. Our results demonstrate that glycine receptor antagonists attenuate NMDA-induced brain injury in vivo.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27636/1/0000012.pd

HA-996 (1-hydroxy-3-aminopyrrolidone-2) selectively reduces (NMDA)-mediated brain damage

The neuroprotective effects of the strychnine-insensitive glycine receptor antagonist, HA-966, against (NMDA)- and quisqualate (QA)-mediated brain injury were determined in perinatal rats. Postnatal day (PND) 7 rats received intrastriatal injections of NMDA (25 nmol) or QA (100 nmol) and then were administered intraperitoneal (i.p.) injections of varying doses of HA-966 or vehicle 15 min later. Animals were sacrificed 5 days later and the degree of brain injury was calculated by comparison of the weights of injected and contralateral cerebral hemispheres. HA-966 selectively reduced the degree of NMDA-mediated brain injury in a dose-dependent manner. However, HA-966 did not attenuate QA-mediated brain injury.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27755/1/0000148.pd