Genomic diversity and population structure of three autochthonous Greek sheep breeds assessed with genome-wide DNA arrays.

In the present study, genome-wide genotyping was applied to characterize the genetic diversity and population structure of three autochthonous Greek breeds: Boutsko, Karagouniko and Chios. Dairy sheep are among the most significant livestock species in Greece numbering approximately 9 million animals which are characterized by large phenotypic variation and reared under various farming systems. A total of 96 animals were genotyped with the Illumina's OvineSNP50K microarray beadchip, to study the population structure of the breeds and develop a specialized panel of single-nucleotide polymorphisms (SNPs), which could distinguish one breed from the others. Quality control on the dataset resulted in 46,125 SNPs, which were used to evaluate the genetic structure of the breeds. Population structure was assessed through principal component analysis (PCA) and admixture analysis, whereas inbreeding was estimated based on runs of homozygosity (ROHs) coefficients, genomic relationship matrix inbreeding coefficients (FGRM) and patterns of linkage disequilibrium (LD). Associations between SNPs and breeds were analyzed with different inheritance models, to identify SNPs that distinguish among the breeds. Results showed high levels of genetic heterogeneity in the three breeds. Genetic distances among breeds were modest, despite their different ancestries. Chios and Karagouniko breeds were more genetically related to each other compared to Boutsko. Analysis revealed 3802 candidate SNPs that can be used to identify two-breed crosses and purebred animals. The present study provides, for the first time, data on the genetic background of three Greek indigenous dairy sheep breeds as well as a specialized marker panel that can be applied for traceability purposes as well as targeted genetic improvement schemes and conservation programs.

Is epinephrine-induced platelet aggregation autoregulated by its metabolic degradation products in vivo?

BACKGROUND: Catecholamines play an important role in platelet activation and aggregation, epinephrine being the most potent one. Catecholamines are substantially increased during stress, exercise or smoking and could result in clinically important platelet activation if their action was not rapidly regulated. In the present study the possible fast regulation of epinephrine-induced platelet aggregation by its metabolic degradation products is investigated. MATERIALS AND METHODS: Human platelet rich plasma (hPRP) and washed rabbit platelets(wRP) were used for the study. The platelets irreversible aggregation induced by epinephrine and ADP were monitored by an aggregometer prior to and after the addition of the catecholamines degradation products metanephrine, 3-methoxy-4-hydroxy-phenyl-glycole-aldehyde (MHPGA),3-methoxy-4-hydroxy-phenyl-mandelic acid (VMA) 3,4-dihydroxy phenyl glycole (DHPG),3,4-Dihydroxy-phenyl-glycole-aldehyde (DHPGA) and the trimethoxy-phenyl-methyl-piperazine(TMP), a known free radical scavenger and calcium antagonist. Linoleic acid-lipoxygenase reaction, in vitro was monitored in the presence and absence of VMA. RESULTS: Metabolic degradation products possessing a methoxy group at position 3 of the phenolic ring markedly inhibited epinephrine and ADP-induced platelet aggregation at microM concentrations. The most potent inhibitor of both agonists was metahephrine, followed by MHPGA and VMA. TMZ also inhibited platelet aggregation at concentrations similar to VMA. Dihydroxy-phenyl compounds failed to induce any inhibition. None of the substances tested induced any aggregatory effect even at high concentrations (1 mM). VMA significantly inhibited linoleic acid-lipoxygenase reaction at 0.1 microM. CONCLUSIONS: Results indicate that catecholamines' degradation products possessing methoxy (-OCH3) groups can rapidly inhibit in vitro and ex vivo epinephrine-induced platelet aggregation. The inhibitory effects of methoxy phenolic derivatives on epinephrine-induced platelet aggregation may possibly be attributed to their free radical scavenging properties. There is substantial evidence to conclude that an internal rapid autoregulation of epinephrine-induced platelet aggregation, caused by its metabolic degradation products, takes place in vivo.