Genetic factors of reaction time performance: DRD4 7-repeat allele associated with slower responses

Abstract

Twin studies indicate substantial inherited components in cognitive abilities. One of the most extensively studied candidate genes of cognitive functioning is the dopamine D4 receptor gene (DRD4), which has been suggested to be related to attentional disorders. Based on reaction time data of 245 Caucasians participating in different cognitive tasks, slower responses characterized the group with the 7-repeat allele. This effect was present in both sexes and was not because of fatigue. To our knowledge, this is the first report on significant association (P = 0.0001) between the DRD4 variable number of tandem repeat (VNTR) polymorphism and response latencies in a non-clinical adult sample. Other studied dopaminergic polymorphisms did not show an association with reaction time. These results illustrate that speed-of-performance measures derived from multiple reaction time tasks using standardization procedures could be promising tools to detect unique genetic effects in the background of cognitive abilities.

EDTA enhanced plant growth, antioxidant defense system, and phytoextraction of copper by Brassica napus L.

“…Increase in net photosynthetic rate may convert light energy more efficiently in photochemical reactions under the combined treatment of EDTA and Cu 2+ which resulted in increased growth and biomass (Table 1). This increase in photosynthetic pigments with EDTA under Cu stress does not coincide with the report of Székely et al (2011). They reported that a decrease in photosynthetic pigments may be due to oxidative stress generated by EDTA.…”

“…Similar results have been reported in sweet sorghum and CAT (e, f), APX (g, h), and soluble protein (i, j) in roots and leaves of B. napus seedlings grown in solution culture with increasing Cu concentrations (0, 50, and 100 μM) treated without and with 2.5 mM EDTA. Different letters indicate that values are significant different at P<0.05 sudangrass seedlings with EDTA application under Cu stress (Székely et al 2011). In this study, the increase in Cu translocation from root to shoot might be due to chelating effects of EDTA (Gunawardena et al 2010).…”

“…EDTA-assisted increase in growth and biomass has been observed in sudangrass and sweet sorghum (Mani et al 2014;Székely et al 2011). In the present study, increase in biomass and plant growth with the addition of EDTA probably occurred due to enhanced efficiency of gas exchange parameters (Fig.…”

Cognitive and neural correlates of the 5-repeat allele of the dopamine D4 receptor gene in a population lacking the 7-repeat allele

“…Like other polymorphisms findings, some of the initial results regarding DRD4 polymorphism with less statistical power cannot be replicated (Kluger et al, 2002). A recent study showed a robust association between the 7-repeat allele and a slow processing speed (Szekely et al, 2011). Another interesting recent finding was the association between the 7-repeat risk allele and decreased performance of the creativity measured by a divergent thinking test in an Israeli sample (Mayseless et al, 2013).…”

“…Previous genetic studies have shown the effects of the 7-repeat allele in several behavioral variables (Szekely et al, 2011) and regional gray matter structures (Durston et al, 2005;Monuteaux et al, 2008;Shaw et al, 2007). In particular, using a large sample size, Shaw et al (2007) have shown that the 7-repeat allele carriers have a thinner right orbitofrontal/inferior prefrontal and posterior parietal cortex.…”