ABSTRACT. Major depressive disorder (MDD) has been associated with the stress response in the brain, which is controlled by the hypothalamicpituitary-adrenal (HPA) axis. This HPA negative feedback mechanism acts via the activation of glucocorticoid receptor, which is encoded by the NR3C1 gene. The methylation status at the promoter of NR3C1 has been correlated with traumatic experiences in early life, which develop into mental disorder. The aim of this study was to examine the potential associations between the methylation status of NR3C1 promoter, gene expression, blood plasma cortisol levels, and adulthood MDD. The study was conducted with 29 MDD patients (9 males, 20 females) and 33 normal individuals (7 males, 26 females). Bisulfite pyrosequencing on 7 CpG dinucleotides in the region showed significantly higher methylation levels at the CpG7 in MDD patients. When separated by gender, the methylation levels differed significantly in females, but not in males. No significant 19072 M. Nantharat et al. ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (4): 19071-19079 (2015) differences between NR3C1 gene expression level and plasma cortisol levels of MDD patients and normal controls were observed. These data suggest that higher levels of methylation at the NR3C1 promoter may be associated with MDD in a gender-specific manner.

Tobacco (Nicotina tabacum) has been introduced to Thailand for hundreds of years. All tobaccos cultivated in the country are legally separated to local (or early-imported) and imported cultivar groups. However, no method could precisely differentiate the two groups, especially from cured leaf samples. Amplified fragment length polymorphism (AFLP) analysis was introduced to estimate genetic polymorphism of 19 tobacco cultivars grown in Thailand. Thirty-two selective primer-combinations were screened on the genomic DNA extracted from cured leaves. Three primer pairs were selected and resulted in 139 scorable AFLP fragments, of which 103 (74.1%) were polymorphic. Genetic relationship analysis revealed clustering patterns of tobacco samples generally following the cultivar groups. Almost all local cultivars were found closely related to Burley and Turkish types of the imported group, but significantly separated from Virginia type. Our finding therefore should be an important knowledge for further research on cultivar identification and genetic improvement of tobaccos.

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