A study of the possible association between adenosine A2A receptor gene polymorphisms and attention‐deficit hyperactivity disorder traits

The adenosine A_2A receptor (ADORA2A) is linked to the dopamine neurotransmitter system and is also implicated in the regulation of alertness, suggesting a potential association with attention‐deficit hyperactivity disorder (ADHD) traits. Furthermore, animal studies suggest that the ADORA2A may influence ADHD‐like behavior. For that reason, the ADORA2A gene emerges as a promising candidate for studying the etiology of ADHD traits. The aim of this study was to examine the relationship between ADORA2A gene polymorphisms and ADHD traits in a large population‐based sample. This study was based on the Child and Adolescent Twin Study in Sweden (CATSS), and included 1747 twins. Attention‐deficit hyperactivity disorder traits were assessed through parental reports, and samples of DNA were collected. Associations between six single nucleotide polymorphisms (SNPs) and ADHD traits were examined, and results suggested a nominal association between ADHD traits and three of these SNPs: rs3761422, rs5751876 and rs35320474. For one of the SNPs, rs35320474, results remained significant after correction for multiple comparisons. These results indicate the possibility that the ADORA2A gene may be involved in ADHD traits. However, more studies replicating the present results are warranted before this association can be confirmed .     

Serotonin Depletion-Induced Maladaptive Aggression Requires the Presence of Androgens

The sex hormone testosterone and the neurotransmitter serotonin exert opposite effects on several aspects of behavior including territorial aggression. It is however not settled if testosterone exerts its pro-aggressive effects by reducing serotonin transmission and/or if the anti-aggressive effect of serotonin requires the presence of the androgen. Using the resident intruder test, we now show that administration of the serotonin synthesis inhibitor para-chlorophenylalanine (300 mg/kg x 3 days) increases the total time of attack as well as the percentage amount of social behavior spent on attack but not that spent on threat – i.e. that it induces a pattern of unrestricted, maladaptive aggression – in gonadectomized C57Bl/6 male mice receiving testosterone replacement; in contrast, it failed to reinstate aggression in those not given testosterone. Whereas these results suggest the pro-aggressive effect of testosterone to be independent of serotonin, and not caused by an inhibition of serotonergic activity, the pCPA-induced induction of maladaptive aggression appears to require the presence of the hormone. In line with these findings, pCPA enhanced the total time of attack as well the relative time spent on attacks but not threats also in wild-type gonadally intact male C57Bl/6 mice, but failed to reinstate aggression in mice rendered hypo-aggressive by early knock-out of androgen receptors in the brain (AR^NesDel mice). We conclude that androgenic deficiency does not dampen aggression by unleashing an anti-aggressive serotonergic influence; instead serotonin seems to modulate aggressive behavior by exerting a parallel-coupled inhibitory role on androgen-driven aggression, which is irrelevant in the absence of the hormone, and the arresting of which leads to enhanced maladaptive aggression.     

Polymorphisms in Genes of Relevance for Oestrogen and Oxytocin Pathways and Risk of Barrett’s Oesophagus and Oesophageal Adenocarcinoma: A Pooled Analysis from the BEACON Consortium

Background

The strong male predominance in oesophageal adenocarcinoma (OAC) and Barrett’s oesophagus (BO) continues to puzzle. Hormonal influence, e.g. oestrogen or oxytocin, might contribute.

Methods

This genetic-epidemiological study pooled 14 studies from three continents, Australia, Europe, and North America. Polymorphisms in 3 key genes coding for the oestrogen pathway (receptor alpha (ESR1), receptor beta (ESR2), and aromatase (CYP19A1)), and 3 key genes of the oxytocin pathway (the oxytocin receptor (OXTR), oxytocin protein (OXT), and cyclic ADP ribose hydrolase glycoprotein (CD38)), were analysed using a gene-based approach, versatile gene-based test association study (VEGAS).

Results

Among 1508 OAC patients, 2383 BO patients, and 2170 controls, genetic variants within ESR1 were associated with BO in males (p = 0.0058) and an increased risk of OAC and BO combined in males (p = 0.0023). Genetic variants within OXTR were associated with an increased risk of BO in both sexes combined (p = 0.0035) and in males (p = 0.0012). We followed up these suggestive findings in a further smaller data set, but found no replication. There were no significant associations between the other 4 genes studied and risk of OAC, BO, separately on in combination, in males and females combined or in males only.

Conclusion

Genetic variants in the oestrogen receptor alpha and the oxytocin receptor may be associated with an increased risk of BO or OAC, but replication in other large samples are needed.     

ISMmy1, a novel insertion sequence of Mycoplasma mycoides subsp. mycoides small colony type

A new insertion sequence, ISMmy1, has been identified in the bovine pathogen Mycoplasma mycoides subsp. mycoides biotype small colony (MmymySC). The occurrence of ISMmy1 in 15 MmymySC strains and 12 other mycoplasmas was examined by Southern blotting. All MmymySC strains showed identical hybridisation patterns except for the type strain PG1(T), the vaccine strain T1Sr49, and the strain Afadé, which all had unique patterns. ISMmy1-like sequences were also found in the bovine pathogen Mycoplasma bovis strain Donetta(T) while mycoplasmas that are phylogenetically closer to MmymySC lack ISMmy1. This observation suggests horizontal transfer between MmymySC and M. bovis.     

The CYP19 Gene and Associations with Androgens and Abdominal Obesity in Premenopausal Women

Objective: Elevated androgens in women are associated with type 2 diabetes and are dependent on the conversion to estrogens by aromatase cytochrome P450. Polymorphisms of a tetranucleotide repeat [TTTA]_n in the fourth intron of the CYP19 gene are associated with endocrine‐dependent diseases and were examined in relation to hormone levels and disease risk factors in premenopausal women. Research Methods and Procedures: A population sample of women born in 1956 (n = 270) were genotyped for this polymorphism and the results set in relation to steroid hormones, including saliva cortisol, anthropometric variables, estimates of insulin, glucose and lipid metabolism, and blood pressure. Results: Seven tetranucleotide repeat [TTTA]_n alleles were detected with allelic sizes of 168 to 195 bp, with a TCT deletion/insertion (168/171 bp) upstream of this microsatellite. Smoking was associated with elevated androgens (p = 0.005 to 0.019). Using the median (average stretch, 177.5 bp) as a dividing line, nonsmoking women with the shorter microsatellite had higher free testosterone (p = 0.018) and lower sex hormone binding globulin (p = 0.033). These differences were pronounced with the 168‐bp allele. Such women were also characterized by a less‐substantial decrease of morning cortisols (“unwinding”; p = 0.035) and central obesity (abdominal sagittal diameter, p = 0.049) and had waist/hip circumference ratios of borderline significance (p = 0.064). Discussion: The results indicate that, in premenopausal women, a short microsatellite in the fourth intron of the CYP19 gene, caused by a TCT deletion upstream the [TTTA]_n tract, is associated with elevated androgens, perturbed regulation of the hypothalamic‐pituitary‐adrenal axis, and abdominal obesity.     

Patterns of antigenic expression on human monocytes as defined by monoclonal antibodies

A series of seven monoclonal antibodies directed at determinants on human peripheral blood monocytes were produced and characterized. The antibodies were separated into three groups based on cell distribution and percentages of monocytes bearing antigen. Hybridoma antibodies, termed OKM1, OKM9, and OKM10, recognized antigen(s) expressed on the majority of adherent monocytes, null cells, and granulocytes. The second group, comprising OKM5 and OKM8, reacted with most adherent monocytes and platelets. OKM3 and OKM6, comprising a third group of antibodies, reacted with a subpopulation of adherent monocytes and platelets. OKM antibodies were not expressed on lymphocytes, thymocytes, and lymphoblastoid cells, with the exception of OKM3 which reacted with three B-cell lines. SDS gels of immunoprecipitates formed with OKM antibodies yielded the following tentative molecular weight results: OKM1 and OKM9 antigens appeared to be 160,000 (nonreduced) and 170,000 (reduced); OKM10 precipitated two polypeptides of 170,000 and 115,000 (reduced); OKM5 and OKM8 precipitated a single polypeptide of 88,000 (reduced, nonreduced); OKM6 antigen appeared to be 116,000 (nonreduced) and 130,000 (reduced).     

The influence of sea currents, past disruption of gene flow and species biology on the phylogeographical structure of coastal flowering plants

Aim We investigate the geographical genetic structure of two coastal plant species, Cakile maritima Scop. (Brassicaceae) and Eryngium maritimum L. (Apiaceae), through three sea straits and along one continuous stretch of coast using amplified fragment length polymorphisms (AFLPs). The two species have a similar ecology in that they grow in sandy habitats, but differ in life‐form (annual vs. perennial) and dispersability of seeds by sea water as inferred from floating experiments. The sea straits differ in their geological history and their modern current systems. The primary goal of our study was to test the hypothesis that sea straits have an influence on the geographical patterns of genetic variation at the population level. Location The areas around the Strait of Gibraltar, the Dardanelles, the Bosporus and the Atlantic coast of western France. Methods For both species we investigated AFLP variation in several populations from each area. Bayesian clustering and diversity and differentiation measures were used to analyse the genetic data. Results In most areas the spatial genetic structure was similar between the two species. They share the presence of distinct genetic gaps along the coast through the Strait of Gibraltar and the Bosporus, and these genetic gaps coincide with the straits. Both species show genetic continuity along the coast of western France. A distinct genetic gap was found through the Dardanelles for C. maritima but not for E. maritimum. Main conclusions The study shows that sea straits have an influence on the geographical patterns of genetic variation. Sea currents are inferred to cause the genetic gap through the Strait of Gibraltar. In the Bosporus and, for C. maritima, through the Dardanelles, the genetic gaps found are explained by the past closure of these two straits as well as by present‐day factors. Simulations indicate that the lower differentiation of C. maritima through the Dardanelles than through the Bosporus cannot be explained by the difference in geological history of these two straits. The difference in seed dispersability between the two species is argued to be responsible for the observation that differentiation among genetic clusters is higher in E. maritimum than in C. maritima where a direct comparison is possible.     

Homogeneous assay for real-time and simultaneous detection of thymidine kinase 1 and deoxycytidine kinase activities

Measurement of thymidine kinase-1 (TK1) and deoxycytidine kinase (dCK) activity may be useful in cancer disease management. Therefore, a one-step homogeneous assay for real-time determination of TK1 and dCK was developed by combining enzyme complementation with fluorescent signal generation using primer extension and a quenched probe oligodeoxyribonucleotide system at 37 °C. Complementation, for producing dCTP and TTP from nucleoside substrates, was carried out by dTMP kinase and/or UMP/CMP kinase and nucleoside diphosphate kinase. dNTP was continuously incorporated into a fixed oligodeoxyribonucleotide primer, template, and probe system, and the fluorescent signal was generated by using the combined actions of primer extension and 5′ exonuclease activity of Thermophilus aquaticus (Taq) DNA polymerase for specific relief of fluorescent quenching. Fluorescence was captured at 1-min intervals using a real-time polymerase chain reaction (PCR) instrument. A horizontal threshold line, crossing all sample relative fluorescent units (RFU) values at the level of the RFU of the blank sample at the end of the assay (i.e., 90 min), was drawn, obtaining RFU measurement data in minutes for each sample. Duplex proof of principle was demonstrated by the independent determination of different amounts of dCK and TK1 in combination. R² values of 0.90 were demonstrated with Prolifigen TK-REA U/L reference values obtained from pathological canine and human serum samples.     

No Association between Oxytocin Receptor (OXTR) Gene Polymorphisms and Experimentally Elicited Social Preferences

Background

Oxytocin (OXT) has been implicated in a suite of complex social behaviors including observed choices in economic laboratory experiments. However, actual studies of associations between oxytocin receptor (OXTR) gene variants and experimentally elicited social preferences are rare.

Methodology/Principal Findings

We test hypotheses of associations between social preferences, as measured by behavior in two economic games, and 9 single nucleotide polymorphisms (SNPs) of the OXTR gene in a sample of Swedish twins (n = 684). Two standard economic games, the dictator game and the trust game, both involving real monetary consequences, were used to elicit such preferences. After correction for multiple hypothesis testing, we found no significant associations between any of the 9 single nucleotide polymorphisms (SNPs) and behavior in either of the games.

Conclusion

We were unable to replicate the most significant association reported in previous research between the amount donated in a dictator game and an OXTR genetic variant.     

Recent evolutionary history of the bluethroat (Luscinia svecica) across Eurasia

We analysed mitochondrial DNA (mtDNA) sequences from 154 bluethroats (Luscinia svecica) sampled at 21 sites throughout much of their Eurasian range. A previously reported, single base-pair mtDNA difference between L. s. svecica and L. s. namnetum was inconsistent upon expanded geographical sampling. A significant FST value (0.29) and an isolation-by-distance effect show the existence of geographical differentiation. Phylogenetic analysis of haplotypes revealed northern and southern groups, although lineage sorting is incomplete. There was no geographical structure to the haplotype tree within groups, and currently recognized subspecies were not supported. A minimum evolution tree based on pairwise mtDNA genetic distances among average samples showed the same two broadly distributed northern and southern groups. These groups abut in the centre of the latitudinal range, and were possibly isolated by forest that developed and spread westward over the last 15 000 years. Pairwise FST values averaged 0.16 in the southern group, 0.04 in the northern group, and 0.42 between groups. Mismatch distributions suggested population growth in each group, with that in the south being more recent. In the northern group, the geographical pattern in tau suggested northward and eastward expansion. Analysis of nucleotide diversity suggested westward expansion in the southern group. The northern group had higher nucleotide diversity than the southern group, consistent with a larger current population size in the north. Given the significant FST, incompletely sorted haplotype tree, and broadly patterned minimum evolution tree, L. svevica appears to represent a species at an intermediate stage of differentiation between panmixia and reciprocal monophyly.