Behaviour-related DRD4 polymorphisms in invasive bird populations.

It has been suggested that individual behavioural traits influence the potential to successfully colonize new areas. Identifying the genetic basis of behavioural variation in invasive species thus represents an important step towards understanding the evolutionary potential of the invader. Here, we sequenced a candidate region for neophilic/neophobic and activity behaviour - the complete exon 3 of the DRD4 gene - in 100 Yellow-crowned bishops (Euplectes afer) from two invasive populations in Spain and Portugal. The same birds were scored twice for activity behaviour while exposed to novel objects (battery or slice of apple) in captivity. Response to novel objects was repeatable (r = 0.41) within individuals. We identified two synonymous DRD4 SNPs that explained on average between 11% and 15% of the phenotypic variance in both populations, indicating a clear genetic component to the neophilic/neophobic/activity personality axis in this species. This consistently high estimated effect size was mainly due to the repeated measurement design, which excludes part of the within-individual nongenetic variance in the response to different novel objects. We suggest that the alternative alleles of these SNPs are likely introduced from the original population and maintained by weak or antagonistic selection during different stages of the invasion process. The identified genetic variants have not only the potential to serve as genetic markers of the neophobic/neophilic/activity personality axis, but may also help to understand the evolution of behaviour in these invasive bird populations.

Candidate gene polymorphisms for behavioural adaptations during urbanization in blackbirds.

Successful urban colonization by formerly rural species represents an ideal situation in which to study adaptation to novel environments. We address this issue using candidate genes for behavioural traits that are expected to play a role in such colonization events. We identified and genotyped 16 polymorphisms in candidate genes for circadian rhythms, harm avoidance and migratory and exploratory behaviour in 12 paired urban and rural populations of the blackbird Turdus merula across the Western Palaearctic. An exonic microsatellite in the SERT gene, a candidate gene for harm avoidance behaviour, exhibited a highly significant association with habitat type in an analysis conducted across all populations. Genetic divergence at this locus was consistent in 10 of the 12 population pairs; this contrasts with previously reported stochastic genetic divergence between these populations at random markers. Our results indicate that behavioural traits related to harm avoidance and associated with the SERT polymorphism experience selection pressures during most blackbird urbanization events. These events thus appear to be influenced by homogeneous adaptive processes in addition to previously reported demographic founder events.

Testing for associations between candidate genes for circadian rhythms and individual variation in sleep behaviour in blue tits.

The regulation of sleep in animals is controlled by environmental factors, homeostatic mechanisms and endogenous circadian oscillators. The molecular mechanisms underlying such circadian oscillators have been described in detail and a variety of genes that are components of these molecular clocks have been reported. In addition to inter-specific variation in the temporal organization of sleep, there is significant intra-specific variation in different organisms. From numerous studies in humans it is known that polymorphisms in the regulatory clock genes are causing such variation but knowledge about associations between naturally occurring polymorphisms and sleep patterns in wild animals is scarce. In this study, we investigated the phenotypic sleep correlates of eleven previously described polymorphisms in seven candidate genes within a free-living blue tit Cyanistes caeruleus population. We detected associations between four single nucleotide polymorphisms and three of the nine tested sleep parameters representing temporal organization. Awakening time was associated with polymorphisms in AANAT and PERIOD2, morning latency with a polymorphism in CKIε and the duration of the longest sleep bout with a second polymorphism in AANAT. However, by a permutation procedure we showed that the number of significant results and the most significant association has a study-wide likelihood of 46.7 and 5.9 % respectively. Further replication studies are needed to evaluate the potential associations.

Avian genome evolution: insights from a linkage map of the blue tit (Cyanistes caeruleus).

We provide a first-generation linkage map of the blue tit (Cyanistes caeruleus), a passerine within the previously genetically uncharacterized family Paridae, which includes 91 orthologous loci with a single anchored position in the chicken (Gallus gallus) sequence assembly. The map consists of 18 linkage groups and covers 935 cM. There was highly conserved synteny between blue tit and chicken with the exception of a split on chromosome 1, potential splits on chromosome 4 and the translocation of two markers from chromosome 2 and 3, respectively, to chromosome 5. Gene order was very well conserved for the majority of chromosomes, an exception being chromosome 1 where multiple rearrangements were detected. Similar results were obtained in a comparison to the zebra finch (Taeniopygia guttata) genome assembly. The recombination rate in females was slightly higher than in males, implying a moderate degree of heterochiasmy in the blue tit. The map distance of the blue tit was approximately 78% of that of the Wageningen chicken broiler population, and very similar to the Uppsala chicken mapping population, over homologous genome regions. Apart from providing insights into avian recombination and genome evolution, our blue tit linkage map forms a valuable genetic resource for ecological and evolutionary research in Paridae.

Search for informative polymorphisms in candidate genes: clock genes and circadian behaviour in blue tits.

The identification of functional polymorphisms in genes that underlie behavioural trait variation is a challenging but intriguing task in evolutionary biology. Given the wealth of genomic data and the increasing number of genotype-phenotype association studies in model organisms, one can ask whether and how this information can be used for non-model organisms. Here we describe two strategies to search for likely functional polymorphisms in candidate genes in a bird species that has been intensively studied by behavioural and population ecologists, the blue tit Cyanistes caeruleus. In the first approach we searched for repeating elements in coding regions of the genome using information about repeats in Gallus gallus genes. The rationale is that tandem-repeat elements have a high potential to be polymorphic and functional. The second strategy aimed to replicate reported genotype-phenotype association studies by extrapolating results from model organisms to our study species. Both strategies showed high success rates with respect to finding homologous gene regions and potentially informative genetic variants in the genes AANAT, ADCYAP1, CKIepsilon, CLOCK, CREB1, NPAS2 and PERIOD2.

The sepiapterin reductase gene region reveals association in the PARK3 locus: analysis of familial and sporadic Parkinson's disease in European populations.

BACKGROUND: Parkinson's disease is a genetically complex disease with mixed mode of inheritance. Recently, a haplotype across the sepiapterin reductase (SPR) gene, which is located in the PARK3 linkage region, was shown to modulate age of onset of Parkinson's disease in sibships from North America. OBJECTIVE: To make a thorough assessment of the SPR gene region in sporadic Parkinson's disease. METHODS: A linkage study in 122 European sibship families with five microsatellite and 17 single nucleotide polymorphism (SNP) markers in and around the SPR gene region, and an association analysis in 340 sporadic cases of Parkinson's disease and 680 control subjects from Germany with 40 SNPs. Linkage was evaluated by non-parametric linkage scores and genotypic or haplotype association was tested by regression analysis, assuming different risk effect models. RESULTS: Significant LOD scores between 2 and 3 were obtained at the two SPR-flanking markers D2S2110 and D2S1394 and seven SNP markers around the SPR gene. We found the previously reported promoter SNP rs1876487 also significantly associated with age of onset in our sib pair families (p-value 0.02). One strong linkage disequilibrium (LD) block of 45 kb including the entire SPR gene was observed. Within this LD block all 14 inter-correlated SNPs were significantly associated with Parkinson's disease affection status (p-value 0.004). CONCLUSIONS: DNA polymorphisms in a highly intercorrelated LD block, which includes the SPR gene, appear to be associated with both sporadic and familial Parkinson's disease. This confirms a previous study showing that SPR potentially modulates the onset of or risk for Parkinson's disease.

MitoP2, an integrated database on mitochondrial proteins in yeast and man.

The aim of the MitoP2 database (http://ihg.gsf.de/mitop2) is to provide a comprehensive list of mitochondrial proteins of yeast and man. Based on the current literature we created an annotated reference set of yeast and human proteins. In addition, data sets relevant to the study of the mitochondrial proteome are integrated and accessible via search tools and links. They include computational predictions of signalling sequences, and summarize results from proteome mapping, mutant screening, expression profiling, protein-protein interaction and cellular sublocalization studies. For each individual approach, specificity and sensitivity for allocating mitochondrial proteins was calculated. By providing the evidence for mitochondrial candidate proteins the MitoP2 database lends itself to the genetic characterization of human mitochondriopathies.

Neonatal septal implants: development of afferent lamination in the rat dentate gyrus.

The technique of tissue implantation into neonatal rats was used to assess mechanisms underlying the development of afferent lamination in the rat hippocampal formation. Septal nuclei, dissected from the brains of rat embryos (E17-E20), were implanted into the occipital or entorhinal cortex of 2--3 day old neonates that simultaneously received fimbrial transections to remove hippocampal innervation by native septal efferents. As visualized with acetylcholinesterase (AChE) histochemistry, the distribution of enzyme activity in implant-innervated hippocampi is qualitatively identical to the pattern in unoperated animals. Fibers from septal implants placed into the entorhinal cortex, appear to interact with commissural/associational afferents and produce altered laminar zones in the dentate gyrus.

Mutagenicity of constituents identified in pulp and paper mill effluents using the Salmonella/mammalian-microsome assay.

About 300 compounds have been reported in the literature as constituents of pulp-mill effluent. Previously, in our screening program, 10 resin acids identified in effluent were examined for potential mutagenicity in the Salmonella/mammalian-microsome assay. Neoabietic acid was the only resin acid which was found to be mutagenic. Now, a program to screen for mutagenicity of 48 additional compounds, belonging to chemical classes of chlorinated aliphatic and aromatic hydrocarbons, phenols, aldehydes, quinones, and carboxylic acids, has been completed. Only 2 of these compounds, tetrachloropropene and pentachloropropene, were found to be mutagenic, showing dose-related increases in His+ reversion mutations, in the standard Salmonella test. Metabolic activation with a preparation of Aroclor 1254-induced liver homogenate (S9) greatly reduced the mutagenic responses of these 2 compounds. Modifications of the Salmonella test for volatile mutagens enabled the detection of the mutagenicity of 3 additional chlorinated aliphatic hydrocarbons dichloromethane, dichloroethane and trichloroethane.

Autosomal dominant spastic paraplegia with peripheral neuropathy maps to chr12q23-24.

OBJECTIVE: Hereditary spastic paraplegias (HSP) are genetically exceedingly heterogeneous. To date, 37 genetic loci for HSP have been described (SPG1-41), among them 16 loci for autosomal dominant disease. Notwithstanding, further genetic heterogeneity is to be expected in HSP, as various HSP families do not link to any of the known HSP loci. In this study, we aimed to map the disease locus in a German family segregating autosomal dominant complicated HSP. METHODS: A genome-wide linkage analysis was performed using the GeneChip Mapping 10Kv2.0 Xba Array containing 10,204 SNP markers. Suggestive loci were further analyzed by mapping of microsatellite markers. RESULTS: One locus on chromosome 12q23-24, termed SPG36, was confirmed by high density microsatellite fine mapping with a significant LOD score of 3.2. SPG36 is flanked by markers D12S318 and D12S79. Linkage to SPG36 was excluded in >20 additional autosomal dominant HSP families. Candidate genes were selected and sequenced. No disease-causing mutations were identified in the coding regions of ATXN2, HSPB8, IFT81, Myo1H, UBE3B, and VPS29. SPG36 is complicated by a sensory and motor neuropathy; it is therefore the eighth autosomal dominant subtype of complicated HSP. CONCLUSION: We report mapping of a new locus for autosomal dominant hereditary spastic paraplegia (HSP) (SPG36) on chromosome 12q23-24 in a German family with autosomal dominant HSP complicated by peripheral neuropathy.

A splice site variant in the sodium channel gene SCN1A confers risk of febrile seizures.

OBJECTIVE: Our aim was to investigate whether the risk of febrile seizures is influenced by a common functional polymorphism in the sodium channel gene SCN1A. This single nucleotide polymorphism (IVS5N+5 G>A, rs3812718) was shown to modify the proportion of two alternative transcripts of the channel. METHODS: We performed an exploratory case-control association analysis in 90 adult epilepsy patients with childhood febrile seizures vs 486 epilepsy patients without a history of febrile seizures and also vs 701 population controls. In the replication step, we investigated children with febrile seizures without concomitant epilepsy at the time of their inclusion. We compared the genotypes of 55 of those children against population controls and performed a within-family association analysis in an additional 88 child-parent trios with febrile seizures. RESULTS: We observed a significant association of the splice-site interrupting A-allele with febrile seizures (p value in the exploratory step: 0.000017; joint p value of the replication: 0.00069). Our data suggest that the A-allele of this variant confers a threefold genotype relative risk in homozygotes and accounts for a population attributable fraction of up to 50% for the etiology of febrile seizures. CONCLUSIONS: The A-allele of the SCN1A single nucleotide polymorphism IVS5N+5 G>A (rs3812718) represents a common and relevant risk factor for febrile seizures. A limitation of the present study is that patients of the exploratory and replication steps differed in aspects of their phenotype (febrile seizures with and without additional epilepsy).

No association of vacuolar protein sorting 26 polymorphisms with Alzheimer's disease.

Using a case-control sample we evaluated a possible involvement of the Vacuolar protein sorting 26 (VPS26) gene in the pathogenesis of AD. VPS26 located at 10q22.1 denotes a retromer subunit functionally involved in the cellular trafficking of Memapsin 2 (BACE). Genotyping of eight single nucleotide polymorphisms covering the complete VPS26 gene and haplotypic analysis revealed no association with AD. Thus, we conclude that VPS26 can be excluded as a major positional and functional candidate gene conferring risk to AD.

Comprehensive association analysis of the NOS2A gene with Parkinson disease.

Inducible nitric oxide synthase (NOS2A) may be involved in the oxidative stress pathology of Parkinson disease (PD). Two previous studies reported an association of a single nucleotide polymorphism (rs1060826) with PD. A replication study of 340 German patients and 680 controls showed no significant association between 12 genotyped polymorphisms and PD. NOS2A is therefore not a major susceptibility locus in our relatively young sample population.

Possible gender-dependent association of vascular endothelial growth factor (VEGF) gene and ALS.

Individuals homozygous for haplotypes -2578-A/-1154-A/-634-G or -2578-A/-1154-G/-634-G in the promoter/5'UTR of the VEGF gene have a 1.8-fold increased risk of ALS in several European populations. We did not observe any significant association with single markers, or haplotype pairs, in a German sample of 580 sporadic ALS patients and 628 controls. However, the promoter SNP-1154 (rs1570360) was associated with affection status in women (p = 0.036), suggesting that the VEGF effect may be dependent on the sex ratio of the sample.

Strong genetic evidence for association of TOR1A/TOR1B with idiopathic dystonia.

Recently, association of a TOR1A(DYT1)/TOR1B risk haplotype with common forms of idiopathic dystonia has been reported in the Icelandic population. Here we report a strong association of two single nucleotide polymorphisms within or in close proximity to the TOR1A 3'UTR, with the lowest p value being 0.000008, in a larger cohort of German and Austrian patients with predominantly focal sporadic dystonia.

Carpal tunnel syndrome in pregnancy.

One thousand consecutive postpartum patients were interviewed by questionnaire to establish the incidence of carpal tunnel syndrome in pregnancy. Hand symptoms had been noted by 34%: 25% had had symptoms of carpal tunnel syndrome, 2% symptoms of ulnar nerve compression and 7% ill defined hand symptoms. Maternal and fetal age, parity and weight change did not correlate with the presence of symptoms. The rate of ring removal because of swelling was twice as great for the symptomatic women (73%) as for the asymptomatic women (36%), and the rates of pre-eclampsia, hypertension and edema were higher for the women with symptoms. Three quarters of the women had bilateral symptoms, and half of the multigravidas had had similar symptoms in previous pregnancies. Hand function and sleep were disturbed in 75% of the symptomatic women, yet only 46% of all those with symptoms mentioned their symptoms to their doctors; treatment was given to only 16% (35% of those who complained), and relief was obtained by only half of these.

Mutagenicity of resin acids identified in pulp and paper mill effluents using the Salmonella/mammalian-microsome assay.

Ten resin acids which have been identified as constituents of pulp and paper mill effluents have been examined for potential mutagenicity in the Salmonella/mammalian-microsome assay. Only neoabietic acid has been found to be mutagenic. Neoabietic acid showed dose-related increases in mutagenicity in strains TA1535, TA100, TA1538, and TA98, but not in strain TA1537. Metabolic activation with a preparation of Aroclor 1254-induced liver homogenate (S9) slightly reduced the mutagenic responses. Negative responses were found for abietic acid, dehydroabietic acid, levopimaric acid, 7-oxodehydroabietic acid, monochlorodehydroabietic acid, dichlorodehydroabietic acid, pimaric acid, isopimaric acid, and sandaracopimaric acid.

Ultrastructural observations on giardiasis in a mouse model. II. Endosymbiosis and organelle distribution in Giardia muris and Giardia lamblia.

Ultrastructural observations of Giardia muris in a mouse model revealed endosymbiotic microbes not previously reported in Giardia. Endosymbionts 240--360 nm wide, 600--1,400 nm long, and with an internal structure similar to that of bacilli were not seen entering Giardia but were found and appeared to divide within Giardia. No evidence was found of digestion of the endosymbionts by the giardia host in either the trophozoite or the cyst form. Endosymbionts were concentrated centrally around the nuclear area and were uncommon in peripheral feeding regions. The same cellular organelles seen in G. muris were found in Giardia lamblia from human jejunal biopsy material, but no endosymbionts were identified in G. lamblia trophozoites from the seven patients examined. Endosymbionts within Giardia may be found to alter trophozoite pathogenicity, metabolism, range of infectivity, antigenic surface characteristics, and host specificity, as they do in other protozoa.