Fig.1.uStrategies for providing toxicological therapeutic insights about cannabinoid biology using zebrafish. Cannabinoid biology may be elucidated in the zebrafish using a tandem of pharmacological and genetic approaches. Pharmacological approaches should include investigations of endocannabinoids, phytocannabinoids, and synthetic cannabinoids. Genetic approaches should include the use of targeted PD173955
editing approaches such as a custom nuclease technology, as well as untargeted genome editing approaches such as transposon systems. The use of pharmacological and genetic approaches with the zebrafish model will reveal novel toxicological and therapeutic insights about cannabinoid biology.Figure optionsDownload full-size imageDownload high-quality image (710 K)Download as PowerPoint slide
AcknowledgmentsThe National Institutes of Health (Grant: DA032194), Mayo Graduate School, and Mayo Foundation for Medical Education and Research provided funding for our work. The Mayo Clinic Division of Media Support Services assisted with the development of Fig.1. The National Institutes of Health (Grant: RR15402-01) provided funding for the work referenced in this manuscript that has been published on The Zebrafish Model Organism Database available at zfin.org (Thisse et al., 2001).
LD, Linkage disequilibrium; FXS, Fragile X syndrome; STR, Short tandem repeat
Polymorphic markers; Linkage analysis; Haplotype frequency; Iranian population
Fragile X syndrome (FXS) which is caused by mutation in the FMR1 gene, is the most prevalent form of X linked mental retardation in the world (1/4000 males). CGG repeat expansion, located in the 5-untranslated region of the FMR1 gene, is the main cause of inactivation of the gene ( Garber et al., 2008uanduRousseau et al., 2011).
Direct diagnosis of the disease is based on PCR and southern blot analysis, but because of some technical problems such as i) full mutations heterogeneity, ii) mosaicism in repeat size and methylation, iii) presence of normal X chromosomes
in women, iv) resistance of expanded repeat to PCR because of high GC content, v) preferential amplification of smaller allele in heterozygous patients, and vi) incomplete or absence of methylation in prenatal samples, use of polymorphic DNA markers have been proven to be useful for carrier detection and prenatal diagnosis in families with an affected individuals ( Burlet et al., 2006uanduRousseau et al., 2011). Additionally, the polymorphic markers have been employed to verify the presence of any significant gametic disequilibrium between the FXS mutation and some haplotypes (Chiurazzi et al., 1995). However, the application of polymorphic markers in linkage analysis requires the presence of informative haplotypes in the population under study (Haghighatnia et al., 2012).
The FMR1 gene region contains several polymorphic genetic markers. Polymorphic markers usually show population-based frequency of heterozygosity, which needs to be determined in each population separately. Among the short tandem repeats (STRs) present in the FMR1 gene region, DXS548 and FRAXAC1, two dinucleotide (CA) repeat markers located 150ukb and 7ukb proximal to the FMR1 gene, respectively, have been the most characterized loci used in population studies ( Arrieta et al., 2003, Crawford et al., 2000uanduZhou et al., 2006). Moreover, these markers have been reported as markers associated with FMR1 CGG repeat instability ( Eichler et al., 1996uanduGunter et al., 1998). DXS998, located 400ukb proximal to the FMR1 gene, suggested to have high degree of heterozygosity among a few populations ( Drozd et al., 2003a). However, no investigation has been performed on any STR markers located in the FMR1 gene region in the Iranian population.