Genetic ablation of VIAAT in glycinergic neurons causes a severe respiratory phenotype and perinatal death

Both glycinergic and GABAergic neurons require the vesicular inhibitory amino acid transporter (VIAAT) for synaptic vesicle filling. Presynaptic GABA concentrations are determined by the GABA-synthesizing enzymes glutamate decarboxylase (GAD)65 and GAD67, whereas the presynaptic glycine content depends on the plasma membrane glycine transporter 2 (GlyT2). Although severely impaired, glycinergic transmission is not completely absent in GlyT2-knockout mice, suggesting that other routes of glycine uptake or de novo synthesis of glycine exist in presynaptic terminals. To investigate the consequences of a complete loss of glycinergic transmission, we generated a mouse line with a conditional ablation of VIAAT in glycinergic neurons by crossing mice with loxP-flanked VIAAT alleles with a GlyT2-Cre transgenic mouse line. Interestingly, conditional VIAAT knockout (VIAAT cKO) mice were not viable at birth. In addition to the dominant respiratory failure, VIAAT cKO showed an umbilical hernia and a cleft palate. Immunohistochemistry revealed an almost complete depletion of VIAAT in the brainstem. Electrophysiology revealed the absence of both spontaneous glycinergic and GABAergic inhibitory postsynaptic currents from hypoglossal motoneurons. Our results demonstrate that the deletion of VIAAT in GlyT2-Cre expressing neurons also strongly affects GABAergic transmission and suggest a large overlap of the glycinergic and the GABAergic neuron population during early development in the caudal parts of the brain

Distribution and phylogeny of Hyalomma ticks (Acari: Ixodidae) in Turkey

The genus Hyalomma includes some of the most medically and veterinarily important tick species in the world. To clarify and identify the current distribution of the species of Hyalomma, field studies were conducted in 65 localities in Turkey and five localities in Cyprus. Additionally, using mitochondrial 12S and 16S ribosomal DNA, specimens of Hyalomma from Turkey, H. excavatum from Cyprus, H. marginatum from Spain and Italy were evaluated together with the available sequences obtained from Genbank. Morphological and molecular analyses demonstrated the presence of four species in Turkey: H. marginatum, H. excavatum, H. aegyptium and H. asiaticum. Hyalomma marginatum is the dominant species in the Central and Northern parts of Turkey, whereas H. excavatum distributes mostly in the Southern parts. Hyalomma asiaticum is restricted to the Southeastern Anatolia. However, some sympatric regions were observed for these species. Phylogenetic trees obtained with Maximum Likelihood method demonstrated five clades. Data supported previous conclusions, but placed H. asiaticum, H. scupense, H. dromedarii and H. aegyptium in different clades with high bootstrap values. Specimens of H. anatolicum group and H. marginatum complex are sister groups. Pairwise distance analyses of these groups showed 2.8 and 3% differences for 12S rDNA and 16S rDNA, respectively. Therefore, additional analyses with the samples from different locations using different markers need to evaluate the exact status of the species of these groups