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At least 145 records · Page 8Linked to original sources
PubMed1999

Are twins' behavioural/emotional problems different from singletons'?

We compared twins with singletons in the National Epidemiological Child Psychiatric Study, which included 122 twins and 5455 singletons, born in 1981 and selected at random. Behavioural and emotional symptoms were assessed in 1989 on the basis of questionnaires filled in by the parents (Rutter Parent Questionnaire) (RA2), teachers (Rutter Teacher Questionnaire) (RB2) and the children themselves (Children's Depression Inventory) (CDI). Parents' reported proportions of probable behavioural/emotional disorders did not differ between the twin and singleton girls, but among the twin boys there was a nonsignificant trend of being more often probably disturbed. Twins were reported to be less disturbed than singletons according to the teachers' assessments. No difference was found between twins and singletons in their self-reports. When analysing parents' reported values of various sum scores, the twin boys obtained slightly higher scores than singletons, while twin girls scored significantly lower on total and emotional disturbances. Twin boys obtained lower mean scores than singletons for probable disorder in the teachers' evaluations, the differences arising mostly in the emotional area. The same type of trend, however nonsignificant, was found among the teachers' evaluations of girls. No significant difference was found in the mean scores for hyperactivity. This large population-based sample suggests that twins may have a lower rate of behavioural problems in childhood than singletons, a finding that has to be taken into account in behavioural genetic studies.

Child↗
PubMed2004

Jonathan Hodgkin.

Jonathan Hodgkin graduated from Oxford in 1971 and then did a PhD with Sydney Brenner at MRC LMB in Cambridge, studying behavioural genetics in the nematode Caenorhabditis elegans. Later, after a couple of years working with myxobacteria as a postdoc in Dale Kaiser's lab at Stanford, he returned to LMB as a staff member, where he remained for most of the subsequent two decades. In the year 2000, he moved to Oxford as Professor of Genetics in the Department of Biochemistry, switching his major research interests from developmental genetics and sex determination to the study of host-pathogen interactions in the worm. For the past ten years, he has acted as curator of the C. elegans genetic map and gene nomenclature, and he is currently President of the Genetics Society of Great Britain.

Animals↗
PubMed2005

The neurodevelopment of human sexual orientation.

One of the most enduring and controversial questions in the neuroscience of sexual behaviour surrounds the mechanisms which produce sexual attraction to either males or females. Here, evidence is reviewed which supports the proposal that sexual orientation in humans may be laid down in neural circuitry during early foetal development. Behaviour genetic investigations provide strong evidence for a heritable component to male and female sexual orientation. Linkage studies are partly suggestive of X-linked loci although candidate gene studies have produced null findings. Further evidence demonstrates a role for prenatal sex hormones which may influence the development of a putative network of sexual-orientation-related neural substrates. However, hormonal effects are often inconsistent and investigations rely heavily on 'proxy markers'. A consistent fraternal birth order effect in male sexual orientation also provides support for a model of maternal immunization processes affecting prenatal sexual differentiation. The notion that non-heterosexual preferences may reflect generalized neurodevelopmental perturbations is not supported by available data. These current theories have left little room for learning models of sexual orientation. Future investigations, across the neurosciences, should focus to elucidate the fundamental neural architecture underlying the target-specific direction of human sexual orientation, and their antecedents in developmental neurobiology.

Androgens↗
PubMed2004

Cholecystokinin-B receptor gene expression in cerebellum, pre-frontal cortex and cingulate gyrus and its association with suicide.

Suicide is a complex behaviour. Genetic and environmental factors are implicated in suicide. Both factors require genes to exert their effects. One gene hypothesized to be involved in the pathophysiology of suicide is cholecystokinin. Alterations in cholecystokinin receptor binding have been reported to be significant in young suicide victims as compared to matched controls in the frontal and cingulate cortex. In this study we report the Cholecystokinin-B gene expression using RT-PCR, between suicide completers [(N = 10); mean age 37.2+/-12 years] and control subjects [(N = 10); mean age 37.6+/-11.9 years]. Cholecystokinin-B gene expression was significantly higher in the cerebellum (P = 0.006), cingulate gyrus (P = 0.024) and pre-frontal cortex (P = 0.017) of suicide completers when compared to their age and sex-matched controls.

Adolescent↗
PubMed1998

The hierarchic structure of fears.

Contemporary theories of fears (and phobias) suggest two kinds of etiologic factors; those common to all fears (factors influencing fear-proneness) and factors specific to particular fears (e.g. specific learning experiences). There also may be etiologic factors of intermediate specificity; factors common to some but not all fears. The present article describes this hierarchic model of fears, which proposes that fears (and phobias) arise from a hierarchy of causal factors, ranging from specific to general. The model is supported by factor-analytic studies of fear inventories and behavioural-genetic studies of twins. However, further research is needed to clarify the number of levels, and to identify environmental, psychobiological, and genetic factors at each level of the causal hierarchy. The hierarchic model of fears represents a call for research. It encourages researchers to take a broad view of etiology by considering factors at various levels of causal specificity.

Arousal↗
PubMedDate not supplied

The role of biological research in supporting policy needs.

Within the UK, the Department for Environment, Food and Rural Affairs (DEFRA) is one of several government departments which undertakes research in support of its policy aims. For example, DEFRA has responsibility for licensing the deposit of materials in the sea in order to protect the environment, public health and prevent interference with other uses of the sea. This includes assessment of pollutant responses in marine organisms. The objectives include assessment of the sub-lethal effect that pollutants have at the cellular, organ and individual level, for example in normal genetic, behavioural and reproductive activity and extrapolation of the potential impact of pollutants to populations. This work helps DEFRA to establish whether individually or in combination, pollutants have an adverse effect on the environment. This paper gives some examples of the research undertaken and demonstrates how biological research can provide cost effective solutions to analytical problems and an opportunity to predict the way in which proposed disposal operations may have an impact on the marine environment. The way such research may influence policy is also discussed.

Ecosystem↗
PubMed2001

Substance abuse in schizophrenia: a review of the literature and a study of correlates in Sweden.

The purpose of the current study is twofold: (a) to provide an overall synthesis of recent research on substance abuse in schizophrenia and (b) to present findings in a Swedish patient sample. Studies conducted since 1990 have found a wide range of abuse prevalence rates, with male gender and younger age as primary correlates. Less certainty exists regarding substance abuse as an independent risk factor for schizophrenia and its further impact on illness course. In a sample of 87 patients attending a psychiatric clinic in Malmö, lifetime prevalence of substance abuse was 48.3%, with abuse debut primarily preceding first contact for psychotic symptoms. Significant correlates of abuse were male gender, family history of substance abuse, and increased rates of hospitalization and criminality, with poorer outcome found in previous as well as current abusers. Alcohol abuse, either solely or in combination with other substances, was the main type of substance abuse. Although the specific factors (social, behavioural, genetic) that predispose schizophrenic patients to substance abuse remain unclear, the predominantly male profile of abusers might suggest a link between substance abuse and the poorer clinical outcome frequently observed, especially in male schizophrenic patients.

Adult↗
PubMed1987

Protostrongylus rufescens: a cytogenetic study.

The diploid chromosome number of Protostrongylus rufescens is 2n = 11 for males and 2n = 12 for females. So, the sex determinism mechanism is XO/XX. The study of the genetic behaviour of this species has been made. In diakinesis stage the bivalents show typical tetrads with cross, phi, and lineal configurations. The division of the sexual chromosome is prereductional for the first meiotic division.

Animals↗
PubMed2005

The receptors and coding logic for bitter taste.

The sense of taste provides animals with valuable information about the nature and quality of food. Bitter taste detection functions as an important sensory input to warn against the ingestion of toxic and noxious substances. T2Rs are a family of approximately 30 highly divergent G-protein-coupled receptors (GPCRs) that are selectively expressed in the tongue and palate epithelium and are implicated in bitter taste sensing. Here we demonstrate, using a combination of genetic, behavioural and physiological studies, that T2R receptors are necessary and sufficient for the detection and perception of bitter compounds, and show that differences in T2Rs between species (human and mouse) can determine the selectivity of bitter taste responses. In addition, we show that mice engineered to express a bitter taste receptor in 'sweet cells' become strongly attracted to its cognate bitter tastants, whereas expression of the same receptor (or even a novel GPCR) in T2R-expressing cells resulted in mice that are averse to the respective compounds. Together these results illustrate the fundamental principle of bitter taste coding at the periphery: dedicated cells act as broadly tuned bitter sensors that are wired to mediate behavioural aversion.

Animals↗
PubMed2003

Retinal function and morphology in two zebrafish models of oculo-renal syndromes.

We characterized visual system defects in two recessive zebrafish mutants oval and elipsa. These mutants share the syndromic phenotype of outer retinal dystrophy in conjunction with cystic renal disorder. We tested the function of the larval visual system in a behavioural assay, eliciting optokinetic eye movements by high-contrast motion stimulation while recording eye movements in parallel. Visual stimulation did not elicit eye movements in mutant larvae, while spontaneous eye movements could be observed. The retina proved to be unresponsive to light using electroretinography, indicative of a defect in the outer retina. Histological analysis of mutant retinas revealed progressive degeneration of photoreceptors, initiated in central retinal locations and spreading to more peripheral regions with increasing age. The inner retina remains unaffected by the mutation. Photoreceptors display cell type-specific immunoreactivity prior to apoptotic cell death, arguing for a dystrophic defect. Genomic mapping employing simple sequence-length polymorphisms located both mutations on different regions of zebrafish linkage group 9. These mutants may serve as accessible animal models of human outer retinal dystrophies, including oculo-renal diseases, and show the general usefulness of a behavioural genetic approach to study visual system development in the model vertebrate zebrafish.

Animals↗
PubMed1999

The long-term culture of porcine urothelial cells and induction of urothelial stratification.

OBJECTIVE: To assess porcine urothelial cell cultures and the in vitro induction of urothelial stratification in long-term cultures, to study their morphological, functional and genetic behaviour, and thus provide potential autologous urothelium for tissue-engineered substitutes for demucosalized gastric or colonic tissue. MATERIALS AND METHODS: Primary cultures of porcine urothelium were established and the cells passaged thereafter. Cell specificity was confirmed by cytokeratin analysis, cell membrane stability assessed using lactate dehydrogenase leakage, cell de-differentiation by gamma-glutamyl transferase activity and genomic stability by karyotype investigations. Histology and scanning electron microscopy were performed to study the cultured cells and the stratified constructs. Furthermore, collagen matrices were tested as cell scaffolds. RESULTS: The cells were cultured for 180 days; 10 subcultures were established during this period. Stratification was induced in a culture flask and on a collagen matrix. Cytokeratins 7, 8, 17 and 18 were expressed in all cultures, and cell membranes were stable, with no evident de-differentiation. The cultures were stable in their genotype and no chromosomal aberrations were found. The histology and immunohistochemistry of the stratified porcine constructs, and cell membrane stability and cell de-differentiation, were compared with those in the human system. CONCLUSION: Pig and human urothelial cells can be cultured over a long period with no signs of senescence. Urothelial stratification can be induced in vitro. The collagen matrix seems to be an excellent scaffold, allowing cell adherence and growth.

Animals↗
PubMed2001

[Cellular surgery with laser in ophthalmology. A review].

This is a review of a number of laser methods, allowing to realize strongly localized, atraumatic, molecular, cellular, and subcellular microeffects. New instruments are the laser tweezers and the laser knife to be used with a microscope (microscopical surgery). Laser tweezers allow fixation, by means of the radiation pressure of molecular, cellular, and subcellular elements, of diameters as small as 1 microm. These may be irradiated atraumatically by means of short-pulsed lasers. A reversible damage of the cell membrane allows to introduce living genetic material into living cells and to reversibly modify their genetic behaviour. Micromanipulation/irradiation of living cells by means of the short-pulse laser method of living cells may be optimal in in-vivo fertilization experiments. Short-pulse laser methods have been tentatively introduced in ophthalmology and highly localized effects have been realized in the trabecular meshwork for the treatment of glaucoma and in the retina in retinal pathology.

Humans↗
PubMed2006

The latent structure of attention-deficit/hyperactivity disorder: a taxometric analysis.

OBJECTIVE: To test whether the latent structure of attention deficit/hyperactivity disorder (ADHD) is best understood as categorical or dimensional in samples of 1774 children (aged 6-12 years) and 1222 adolescents (aged 13-17 years) drawn from an Australian epidemiological study. METHOD: Two taxometric procedures (MAXEIG and MAMBAC) examined ADHD symptom measures assessed by diagnostic interview and parental ratings. RESULTS: Consistent with behavioural genetic research, findings fail to support the view that a latent category underpins ADHD. CONCLUSIONS: ADHD is best modelled as a continuum among both children and adolescents, and no discrete dysfunction can therefore be assumed to cause it. The placement of the diagnostic threshold should therefore be decided on pragmatic grounds (e.g. impairment or need for treatment).

Adolescent↗
PubMed2002

Analytic approaches to twin data using structural equation models.

The classical twin study is the most popular design in behavioural genetics. It has strong roots in biometrical genetic theory, which allows predictions to be made about the correlations between observed traits of identical and fraternal twins in terms of underlying genetic and environmental components. One can infer the relative importance of these 'latent' factors (model parameters) by structural equation modelling (SEM) of observed covariances of both twin types. SEM programs estimate model parameters by minimising a goodness-of-fit function between observed and predicted covariance matrices, usually by the maximum-likelihood criterion. Likelihood ratio statistics also allow the comparison of fit of different competing models. The program Mx, specifically developed to model genetically sensitive data, is now widely used in twin analyses. The flexibility of Mx allows the modelling of multivariate data to examine the genetic and environmental relations between two or more phenotypes and the modelling to categorical traits under liability-threshold models.

Chi-Square Distribution↗
PubMed1998

Structure and genetic stability of mitochondrial genomes vary among yeasts of the genus Saccharomyces.

Several yeast species/isolates belonging to the genus Saccharomyces were examined for the organization of their mtDNAs and ability to generate petite mutants. A general characteristic for all of the mtDNAs tested was that they were very A+T-rich. However, restriction patterns and inducibility of petite mutations revealed a great diversity in the organization and genetic behaviour of mtDNAs. One group of yeasts, Saccharomyces sensu stricto, contains mtDNA ranging in size from 64 to 85 kb. mtDNAs form these yeasts contain a high number of restriction sites that are recognized by the enzymes Haelll and Mspl, which cut specifically in G+C clusters. There are three to nine ori/rep sequences per genome. These yeasts spontaneously generate respiration deficient mutants. Ethidium bromide (Et-Br), at low concentrations, induces a majority of cells to give rise to petites. A second group of yeasts, Saccharomyces sensu lato, contains smaller mtDNAs, ranging in size from 23 to 48 kb, and probably only a few intergenic G+C clusters and no ori/rep sequences. These yeasts also generate petite clones spontaneously. but Et-Br, even when present at high concentrations, does not substantially increase the frequency of petites. In most petite clones from these yeasts only a small fragment of the wild-type molecule is retained and apparently multiplied. A third group, represented by Saccharomyces kluyveri, does not give rise to petite mutants either spontaneously or after induction.

Base Composition↗
PubMed2002

Annotation: The 'effects' of parenting reconsidered: findings, challenges, and applications.

BACKGROUND: Questions remain concerning the 'effects' of parenting on behavioural/emotional problems in children. This annotation discusses recent findings concerning the parenting 'effects' literature and identifies areas in need of further research. METHOD: The review begins by examining theories and definitions of parenting, and then considers research findings on the predictors of parent-child relationships and their effects on behavioural/emotional adjustment in children. Evidence for causal processes are then examined in light of findings emphasizing the need to consider the impact of larger systems on child's well-being, bi-directional processes in parent-child interactions, and alternative hypotheses suggested by behavioural genetics. RESULTS: Different kinds of evidence suggest strong links between parent-child relationship quality and children's well-being, but difficulties remain for drawing causal connections. The need for greater integration among research traditions and the need for theory development are highlighted. In addition, although a substantial and robust research base exists on parent-child relationships, the applicability of these findings to clinical settings is uncertain. CONCLUSIONS: Substantial progress has been made in our understanding of the nature of parent-child relationships and their developmental effects, but a number of basic conceptual and methodological and clinical questions continue to need rigorous study.

Affective Symptoms↗
PubMed2005

Molecular evidence supporting the neoplastic nature of odontogenic keratocyst: a laser capture microdissection study of 15 cases.

AIMS: The bland histology of odontogenic keratocyst (OKC) belies its capacity for aggressive behaviour. Genetic alterations of OKC have not been well studied. We examined the frequency and pattern of allelic imbalance on five different chromosome regions from 15 patients with OKC. METHODS AND RESULTS: Laser-assisted microdissection was performed on formalin-fixed paraffin-embedded tissue. Polymerase chain reaction analysis of extracted DNA targeted five polymorphic DNA markers (D3S1285, D9S161, D11S1316, D13S290, and TP53) representing chromosome regions 3p14, 9p21, 11q23, 13q12.1 and 17p13, respectively. All 15 cases of OKC were informative at a minimum of three of five loci, with 11 informative on all five loci. Twelve of 15 cases (80%) demonstrated loss of heterozygosity (LOH). Seven cases (47%) showed LOH at more than two DNA loci. The frequency of LOH was 5/11 (45%) at D3S1285, 3/15 (20%) at D9S161, 4/14 (29%) at D11S1316, 8/14 (57%) at D13S290 and 3/15 (20%) at TP53. CONCLUSIONS: The majority of OKCs harbour chromosomal abnormalities. This finding supports the supposition that OKCs are neoplastic. Furthermore, OKCs harbour allelic loss at some of the same loci identified in squamous cell carcinoma. This may aid in explaining the rare occurrence of squamous cell carcinoma arising in OKC.

Alleles↗
PubMed2006

Population dynamics of the ectomycorrhizal fungal species Tricholoma populinum and Tricholoma scalpturatum associated with black poplar under differing environmental conditions.

Fungi combine sexual reproduction and clonal propagation. The balance between these two reproductive modes affects establishment dynamics, and ultimately the evolutionary potential of populations. The pattern of colonization was studied in two species of ectomycorrhizal fungi: Tricholoma populinum and Tricholoma scalpturatum. The former is considered to be a host specialist whereas T. scalpturatum is a generalist taxon. Fruit bodies of both basidiomycete species were mapped and collected over several years from a black poplar (Populus nigra) stand, at two different sites. Multilocus genotypes (= genets) were identified based on the analysis of random amplified polymorphic DNA (RAPD) patterns, inter-simple sequence repeat (ISSR) patterns and restriction fragment length polymorphisms (RFLPs) in the ribosomal DNA intergenic spacer (rDNA IGS). The genetic analyses revealed differences in local population dynamics between the two species. Tricholoma scalpturatum tended to capture new space through sexual spores whereas T. populinum did this by clonal growth, suggesting trade-offs in allocation of resources at the genet level. Genet numbers and sizes strongly differ between the two study sites, perhaps as a result of abiotic disturbance on mycelial establishment and genet behaviour.

Agaricales↗