Genotyping and haplotyping of the dopamine D4 receptor gene by capillary electrophoresis

Electrochemical sensor based on dual-template molecularly imprinted polymer and nanoporous gold leaf modified electrode for simultaneous determination of dopamine and uric acid

A novel electrochemical sensor based on dual-template molecularly imprinted polymer (MIP) with nanoporous gold leaf (NPGL) was established for the simultaneous determination of dopamine (DA) and uric acid (UA). NPGL acts as an enlarged loading platform to enhance sensing capacity, and the MIP layer was synthesized in situ in the presence of monomer and dual templates (DA and UA) to provide specific recognition. Under the optimal conditions, the sensor shows a good linear range of 2.0~180 μM for DA at a working potential of 0.15 V (vs. Ag/AgCl) and 5.0~160 μM for UA at 0.35 V (vs. Ag/AgCl), with the respective detection limit of 0.3 μM and 0.4 μM (S/N = 3). Good selectivity of the sensor to its dual templates was confirmed as the sensing signals are significantly different between templates and interfering species. The responses maintained higher than 96% of the initial values after 30-day storage, and the day-to-day relative standard deviation is less than 3.0%. Real sample simultaneous determination of DA and UA was conducted with bovine serum, and the results were in good agreement with those from high-performance liquid chromatography. It can be concluded that this work offers a reliable, facile, fast, and cost-effective method of simultaneous quantification of two or more chem-/bio-molecules. Graphical abstract.

Simultaneous and sensitive determination of ascorbic acid, dopamine and uric acid via an electrochemical sensor based on PVP-graphene composite

A method with high sensitivity, good accuracy and fast response is of ever increasing importance for the simultaneous detection of AA, DA and UA. In this paper, a simple and sensitive electrochemical sensor, which based on the polyvinylpyrrolidone (PVP)-graphene composite film modified glassy carbon electrode (PVP-GR/GCE), was presented for detecting ascorbic acid (AA), dopamine (DA) and uric acid (UA) simultaneously. The PVP-GR/GCE has excellent electrocatalytic activity for the oxidation of AA, DA and UA. The second-order derivative linear sweep voltammetry was used for the electrochemical measurements. The peak potential differences of DA-AA, DA-UA, and UA-AA (measured on the PVP-GR/GCE) were 212, 130 and 342 mV respectively. Besides, the over potential of AA, DA and UA reduced obviously, so did the peak current increase. Under the optimum conditions, the linear ranges of AA, DA and UA were 4.0 μM–1.0 mM, 0.02–100 μM, and 0.04–100 μM, respectively. The detection limits were 0.8 μM, 0.002 μM and 0.02 μM for AA, DA, and UA. The electrochemical sensor presented the advantages of high sensitivity and selectivity, excellent reproducibility and long-term stability. Furthermore, the sensor was successfully applied to the analysis of real samples.

Detection of haplotype mutations of the MD-2 gene promoter associated with Der p2-induced allergy using a nanostructured biosensor

Group 2 allergens (Der p2) have been reported to be a major cause of the human immune response to dust mite allergens. In this study, we have demonstrated for the first time the effective differentiation between haplotype mutation and normal genes in the MD-2 gene promoter using a nanostructured biosensor. A 70-mer gene fragment containing the haplotype of two single nucleotide polymorphisms in the MD-2 gene promoter region was used as a probe to detect haplotype mutations associated with Der p2-induced allergy. Discrimination was achieved using electrochemical impedance spectroscopy. The discrimination experiments employed 30 haplotype mutation samples and 30 normal target samples. The haplotype mutation samples and normal target samples could be clearly discriminated, even using samples produced by a five-cycle polymerase chain reaction process. The time and cost of sample preparation for the polymerase chain reaction process in the clinical setting can thus be reduced.

5′ UTR polymorphism of dopamine receptor D1 (DRD1) associated with severity and temperament of alcoholism

Multiple dopamine receptors in the dopaminergic system may be prime candidates for genetic influence on alcohol abuse and dependence due to their involvement in reward and reinforcing mechanisms. Genetic polymorphisms in dopamine receptor genes are believed to influence the development and/or severity of alcoholism. To examine the genetic effects of the Dopamine Receptor D1 (DRD) gene family (DRD1-DRD5) in the Korean population, 11 polymorphisms in the DRD gene family were genotyped and analyzed in 535 alcohol-dependent subjects and 273 population controls. Although none of the polymorphisms of DRD1-5 genes were found to be associated with the risk of alcoholism, one 5' UTR polymorphism in the DRD1 (DRD1-48A>G) gene was significantly associated with severity of alcohol-related problem, as measured by the Alcohol Use Disorders Identification Test (AUDIT) in a gene dose-dependent manner, i.e., 24.37 (+/-8.19) among patients with -48A/A genotype, 22.37 (+/-9.49) among those with -48A/G genotype, and 17.38 (+/-8.28) among those with -48G/G genotype (P=0.002). The genetic effects of DRD1-48A>G were further analyzed with other phenotypes among alcohol-dependent subjects. Interestingly, the DRD1-48A>A genotype was also found to be associated with novelty seeking (NC), harm avoidance (HA), and persistence (P) (P =0.01, 0.02, and 0.003, respectively). The information derived from this study could be valuable for understanding the genetic factors involved in alcoholic phenotypes and genetic distribution of the DRD gene family, and could facilitate further investigation in other ethnic groups.

Validation of a tentative microsatellite marker for the dopamine D4 receptor gene by capillary gel electrophoresis

Two to four-basepair-short tandem repeats (i.e. microsatellites) are broadly utilized as genetic markers for mapping disease loci in whole genome search analyses. Based on their close vicinity on chromosome 11, the D11S1984 microsatellite was anticipated as a tentative marker for the dopamine D4 receptor gene. A capillary gel electrophoresis based genotype analysis method and an in-house made computational tool was developed for the analysis of the D11S1984 microsatellite marker to examine a healthy Hungarian population of n=106. The data obtained did not suggest significant linkage between the D11S1984 marker and the DRD4 gene.

Rapid quantification of human complement component C4A and C4B genes by capillary gel electrophoresis

Complement component 4 (C4) is an important plasma protein playing a major role in the human defense mechanism against infectious diseases and inflammatory processes. The C4A and C4B genes, encoding the two isoforms of complement 4, are located in the nuclear serine/threonine protein kinase-C4A or B gene-cytochrome 21-hydroxylase-tenascin X module (RP-C4-CYP21-TNX) and manifested by variable copy numbers among individuals between zero to six in the human diploid genome. Quantification of the C4A and C4B genes has great clinical importance since unbalanced production of C4A and C4B proteins might be associated with pathological immune processes. Albeit, high-throughput analysis methods for C4 gene dosage determination are not yet available. Here we present a novel combination of allele-specific PCR and CGE separation for rapid quantification of the C4A and C4B genes where a single-step, single-tube PCR reaction generates two allele-specific (C4A and C4B) and two control amplicons, followed by CGE analysis of the four fragments. The method presented in this paper enables automated and high-throughput gene dosage analysis of large sample cohorts.

Haplotyping by capillary electrophoresis

The investigation of the genetic background and phenotype structures of complex diseases, such as cardiovascular or psychiatric disorders and tumors, is one of the most scrutinized fields of the post genomic era. Besides the multiplex analysis of genetic markers and polymorphisms throughout the whole genome, more and more attention is focused on the interaction between the etiological factors of these traits. Haplotype determination, rather than multiplex genotyping seems to be one of the first building blocks of this endeavor. This review focuses on the importance and theoretical background of haplotyping, and summarizes the recent examples of novel and emerging haplotyping techniques by capillary gel electrophoresis based DNA fragment analysis, a powerful tool for the examination of the inheritance of complex traits.