RESUMO
Pilosella piloselloides var. praealta (syn. P. praealta; Hieracium praealtum) is a versatile model used to study gametophytic apomixis. In this system apomixis is controlled by three loci: one that controls the avoidance of meiosis (LOA), one that controls the avoidance of fertilization (LOP) and a third that controls autonomous endosperm formation (AutE). Using a unique polyhaploid mapping approach the LOP locus was mapped to a 654 kb genomic interval syntenic to linkage group 8 of Lactuca sativa. Polyhaploids form through the gametophytic action of a dominant determinant at LOP, so the mapped region represents both a functional and a physical domain for LOP in P. piloselloides. Allele sequence divergence (ASD) analysis of the PARTHENOGENESIS (PAR) gene within the LOP locus revealed that dominant PAR alleles in Pilosella remain highly similar across the genus, whilst the recessive alleles are more divergent. A previous report noted that dominant PAR alleles in both Pilosella and Taraxacum are modified by the presence of a class II transposable element (TE) in the promoter of the gene. This observation was confirmed and further extended to the related genus Hieracium. Sufficient differences were noted in the structure and location of the TE elements to conclude that TE insertional events had occurred independently in the three genera. Measures of allele crossover amongst the polyhaploids revealed that P. piloselloides is an autopolyploid species with tetrasomic inheritance. It was also noted that the dominant determinant of LOP in P. piloselloides could transmit via a diploid gamete (pollen or egg) but not via a haploid gamete. Using this information, a model is presented of how gametophytic apomixis may have evolved in several members of the Lactuceae, a tribe of the Asteraceae.
RESUMO
BACKGROUND: Cannabinoid hyperemesis syndrome is a variant of cyclical vomiting syndrome in a context of chronic cannabis usage. Our aim was to compare French cases to those identified in the international literature in order to further our knowledge of the clinical criteria, pathophysiology and treatments for cannabinoid hyperemesis syndrome. METHODS: We analysed cases reported in the international literature up to 30 June 2017, obtained from the MEDLINE, PsycINFO and The Cochrane Library databases; we selected relevant articles based on title and abstract. We also analysed cases of cannabinoid hyperemesis syndrome reported to the French addictovigilance network. RESULTS: A systematic search through the three databases enabled us to identify 137 articles. Finally, 55 articles were selected as they involved reported cases. In total, 113 cases were reported in these 55 articles. We were thus able to analyse 29 reported French cases of cannabinoid hyperemesis syndrome. Cannabinoid hyperemesis syndrome mainly affects young male subjects who have been smoking cannabis daily for several years. Taking hot baths or showers is the most effective means of relieving the symptoms, while antiemetics and dopamine antagonists do not appear to effective for relieving nausea and vomiting. CONCLUSIONS: French cases display the same characteristics as the cases identified in the international literature. The pathophysiology of cannabinoid hyperemesis syndrome is unclear and several hypotheses have been put forward in the literature. We have only begun to characterise the syndrome, though there is an outbreak of cannabinoid hyperemesis syndrome in France.
