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[Genetic behavioral aspects of agricultural animals].

This paper reviews some experimental methods used in the study of genetic fixed behaviour, some examples of investigations in farm animals as well as some results of the author's studies on the emotionality in pigs are given. Many investigations have been made on the estimation of heritability of behaviour patterns in cattle, pigs, poultry and dogs. Behaviour patterns such as temperament, aggressiveness, and nervousness showed relatively high h2-values; other behaviours like trainability, emotionality, and pre-laying showed relatively low values. Selection experiments were carried out in poultry and dogs. The results showed that after a few generations remarkable differences in behaviour patterns between the new lines and the original populations were obvious. Besides the selected traits, modifications occurred in other behaviour patterns and in physiological responses. The emotionality in pigs was investigated with the open field test in 3 genetic groups: German Landrace (DL), Duroc (DU), and cross-breeding between these breeds (DU x DL). Increasing emotionality was displayed by increasing ambulatory activity and vocalization. The lowest activity was observed in the pure breeds, DU showed less signs of emotionality than DL, whereas DU x DL showed the highest of emotionality.

Animals↗

Genes, cognition and dyslexia: learning to read the genome.

Studies of dyslexia provide vital insights into the cognitive architecture underpinning both disordered and normal reading. It is well established that inherited factors contribute to dyslexia susceptibility, but only very recently has evidence emerged to implicate specific candidate genes. In this article, we provide an accessible overview of four prominent examples--DYX1C1, KIAA0319, DCDC2 and ROBO1--and discuss their relevance for cognition. In each case correlations have been found between genetic variation and reading impairments, but precise risk variants remain elusive. Although none of these genes is specific to reading-related neuronal circuits, or even to the human brain, they have intriguing roles in neuronal migration or connectivity. Dissection of cognitive mechanisms that subserve reading will ultimately depend on an integrated approach, uniting data from genetic investigations, behavioural studies and neuroimaging.

Animals↗

Dual role of extramacrochaetae in cell proliferation and cell differentiation during wing morphogenesis in Drosophila.

The Extramacrochaetae (emc) gene encodes a transcription factor with an HLH domain without the basic region involved in interaction with DNA present in other proteins that have this domain. EMC forms heterodimers with bHLH proteins preventing their binding to DNA, acting as a negative regulator. The function of emc is required in many developmental processes during the development of Drosophila, including wing morphogenesis. Mitotic recombination clones of both null and gain-of-function alleles of emc, indicate that during wing morphogenesis, emc participates in cell proliferation within the intervein regions (vein patterning), as well as in vein differentiation. The study of relationships between emc and different genes involved in wing development reveal strong genetic interactions with genes of the Ras signalling pathway (torpedo, vein, veinlet and Gap), blistered, plexus and net, in both adult wing phenotypes and cell behaviour in genetic mosaics. These interactions are also analyzed as variations of emc expression patterns in mutant backgrounds for these genes. In addition, cell proliferation behaviour of emc mutant cells varies depending on the mutant background. The results show that genes of the Ras signalling pathway are co-operatively involved in the activity of emc during cell proliferation, and later antagonistically during cell differentiation, repressing EMC expression.

Alleles↗

Genetic architecture of population differences in oviposition behaviour of the seed beetle Callosobruchus maculatus.

Few studies have examined the genetic architecture of population differences in behaviour and its implications for population differentiation and adaptation. Even fewer have examined whether differences in genetic architecture depend on the environment in which organisms are reared or tested. We examined the genetic basis of differences in oviposition preference and egg dispersion between Asian (SI) and African (BF) populations of the seed beetle, Callosobruchus maculatus. We reared and tested females on each of two host legumes (cowpea and mung bean). The two populations differed in mean oviposition preference (BF females preferred cowpea seeds more strongly than did SI females) and egg dispersion (SI females distributed eggs more uniformly among seeds than did BF females). Observations of hybrid and backcross individuals indicated that only the population difference in oviposition preference could be explained by complete additivity, whereas substantial dominance and epistasis contributed to the differences in egg dispersion. Both rearing host and test host affected the relative magnitude of population differences in egg dispersion and the composite genetic effects. Our results thus demonstrate that the relative influence of epistasis and dominance on the behaviour of hybrids depends on the behaviour measured and that different aspects of insect oviposition are under different genetic control. In addition, the observed effect of rearing host and oviposition host on the relative importance of dominance and epistasis indicates that the genetic basis of population differences depends on the environment in which genes are expressed.

Adaptation, Physiological↗

Breeding success of male brook trout (Salvelinus fontinalis) in the wild.

Competition for females generally results in some males adopting alternative reproductive tactics to acquire matings. For fish, the ecological and evolutionary consequences of these tactics are not well understood because of an inability to link directly the interactions of individuals on the breeding grounds with genetic data. This study combines behavioural observations with genetic estimates of male reproductive success within an intensively studied wild population of lacustrine brook trout (Salvelinus fontinalis). Male brook trout exhibit a conditional reproductive strategy with small males adopting a peripheral position to that of larger dominant males in their proximity to spawning females. Parentage analysis of eggs collected from wild redds confirmed the reproductive success of individual males. Males relegated to peripheral positions during spawning participated frequently in spawning events, but in most cases the first male to spawn was the sole contributor, and no more than two males contributed successfully to a single brood. While behavioural observations of salmonines suggests that reproduction is partitioned among males in a manner dependent upon body size and proximity to spawning females, the genetic evidence from this study suggests a more limited distribution of reproductive success in the field. The genetic contributions of male brook trout are highly skewed towards larger males for this population. A review of the salmonine literature suggests little difference in individual reproductive success for males exhibiting size-related tactics within a conditional mating strategy vs. precocial maturation. Collectively, these genetic studies provide new insights on the evolution of alternative life histories among salmonines.

Animals↗

Behaviour plasticity without learning: phenotypic and genetic variation of naïve Daphnia in an ecological trade-off.

The swimming behaviour of adult Daphnia largely governs their depth, which has a direct effect on both individual foraging success and predation avoidance. We treated individual swimming behaviour as a threshold character and used directional changes in average clonal depth within experimental tubes as a test for character plasticity. We compared the swimming behaviours of two cohabiting, phenotypically similar Daphnia (Daphnia galeata and Daphnia galeata-Daphnia rosea hybrid) to determine (1) whether there is inherited variation (H(2)) for different traits (responses to hunger and predator cues); (2) whether changes in genetic parameters (norm of reaction and character state) across four environments could be simulated by combinations of the presence or absence of a predator cue and high or low hunger levels; and (3) whether these Daphnia would respond to directional selection, particularly in a trade-off environment (high hunger and predator cue treatments). Responses of both D. galeata and the D. galeata-rosea hybrid to hunger and a predator cue and the trade-off environment were plastic. Daphnia galeata expressed significant genetic variation within (H(2)) and between environments (heritability of plasticity). Both the character state and norm of reaction estimates of heritable variation in the hybrid were close to zero. Genetic correlations were positive and stable across six environmental pairs in Daphnia galeata. Most hybrid genetic correlations were not significant. The phenotypic distributions of both D. galeata and the hybrid were bimodal in the trade-off environment. The D. galeata distribution was partly due to between-clone variation and the hybrid distribution was almost entirely due to within-clone variation. Genetic variation expressed by D. galeata in the trade-off environment appears to depend on both clone by environment interactions and stable inherited differences. These results indicate that while plastic phenotypic responses cause a similar opportunity for selection in D. galeata and the hybrid, their responses to selection would be different in the trade-off and in related environments. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗

Endocrine tumours of the gastrointestinal tract: aetiology, molecular pathogenesis and genetics.

Endocrine tumours of the gut and pancreas originate from cells of the diffuse endocrine system and are characterised by the production of a wide variety of bioactive substances including growth factors. Two major tumour categories are distinguished-well-differentiated and poorly differentiated neoplasms-with distinct phenotypes and significantly diverse clinical behaviour. Here, genetic background data are summarised on an anatomical basis for tumours of foregut, midgut and hindgut derivatives. For well-differentiated tumours, independent techniques identified the abnormality of multiple chromosomal sites and genes, pointing to a complex genetic background. Differences in foregut tumours compared with midgut and hindgut tumours are, however, outlined. The multiple endocrine neoplasia syndrome type 1 (MEN1) gene is reported to be involved in about one-third of sporadic foregut endocrine tumours and exceptionally in midgut and hindgut tumours. Similarly, X chromosome markers are associated with malignant behaviour in foregut tumours only. For poorly differentiated carcinomas, a high degree of chromosomal instability is the common genetic trait independent of tumour site and frequently involving the p53 gene.

Carcinoma, Neuroendocrine↗

Genetic evidence for sex-biased dispersal in resident bottlenose dolphins (Tursiops aduncus).

In most mammals males usually disperse before breeding, while females remain in their natal group or area. However, in odontocete cetaceans behavioural and/or genetic evidence from populations of four species indicate that both males and females remain in their natal group or site. For coastal resident bottlenose dolphins field data suggest that both sexes are philopatric to their natal site. Assignment tests and analyses of relatedness based on microsatellite markers were used to investigate this hypothesis in resident bottlenose dolphins, Tursiops aduncus, from two small coastal populations of southeastern Australia. Mean corrected assignment and mean relatedness were higher for resident females than for resident males. Only 8% of resident females had a lower probability than average of being born locally compared to 33% of resident males. Our genetic data contradict the hypothesis of bisexual philopatry to natal site and suggest that these bottlenose dolphins are not unusual amongst mammals, with females being the more philopatric and males the more dispersing sex.

Animals↗

Behavioural responses of farm mink towards familiar and novel food.

The study aimed to (i) describe the response of farmed mink towards familiar and novel food, and (ii) assess the suitability of using novel food in order to measure fear responses in mink. A total of 48 farm mink from two behaviourally selected genetic lines were caged individually with one standardised daily feeding. The experimental feedings were carried out in a balanced order on 2 successive days. Behaviour of the mink was video recorded for 10min after food provision. In general, the mink were reluctant to approach and eat the novel food compared to familiar food, which indicates a neophobic feeding strategy, i.e. increased latency to come close to (P<0.01) and eat (P<0.001) the novel food, and a higher frequency (P<0.001) and a longer duration (P<0.001) of sniffing. Provision of unknown food items may be used to evaluate fear responses in mink since mink respond reluctantly towards novel food. However, high inter-individual variation in the present study obliterated a previously shown difference between confident and fearful mink, suggesting that this method for measuring fear responses in mink is appropriate only on a large animal material.

Journal Article↗

Effect of low stressful temperature on genetic variation of five quantitative traits in Drosophila melanogaster.

A half-sib analysis was used to investigate genetic variation for three morphological traits (thorax length, wing length and sternopleural bristle number) and two life-history traits (developmental time and larva-to-adult viability) in Drosophila melanogaster reared at a standard (25 degrees C) and a low stressful (13 degrees C) temperature. Both phenotypic and environmental variation showed a significant increase under stressful conditions in all traits. For estimates of genetic variation, no statistically significant differences were found between the two environments. Narrow heritabilities tended to be higher at 13 degrees C for sternopleural bristle number and viability and at 25 degrees C for wing length and developmental time, whereas thorax length did not show any trend. However, the pattern of genetic variances and evolvability indices (coefficient of genetic variation and evolvability), considered in the context of literature evidence, indicated the possibility of an increase in additive genetic variation for the morphological traits and viability and in nonadditive genetic variation for developmental time. The data suggest that the effect of stressful temperature may be trait-specific and this warns against generalizations about the behaviour of genetic variation under extreme conditions.

Analysis of Variance↗

The Nutrition Society Medical Lecture. Obesity: from molecules to man.

Obesity is now a major public health problem in both developed and developing countries. In the UK over 16% men and 17.5% women are obese, an increase of more than 100% since 1980. However, interventions to prevent and treat obesity are hampered by an inadequate understanding of the aetiology of this condition. The present paper considers the current state of knowledge regarding the causes of obesity, including some of the genetic, metabolic, behavioural and environmental factors which influence energy balance. The present paper comprises The Nutrition Society Medal Lecture and focuses in particular on the research carried out at the MRC Dunn Nutrition Centre in Cambridge. It argues that despite decades of intensive research there is relatively little evidence of genetic or metabolic defects to explain the majority of cases of human obesity. Instead we must look to behavioural and/or environmental factors which may be underpinning the current epidemic of obesity.

Diet↗

Protein polymorphisms detected by two-dimensional electrophoresis: an analysis of overall informativeness of a panel of linkage markers.

Forty-two independent polymorphic loci are detectable by two-dimensional electrophoresis (2DE) of four peripherally accessible human tissues. Fifteen have been chromosomally mapped and, taken together, these constitute a useful panel of markers for genetic linkage studies in humans. An analysis of the overall informativeness for linkage of this panel of markers is presented, taking into account the effect of varying the number of families or matings studies. Use of 2DE polymorphic markers for linkage of genetically determined behaviour traits in humans and mice is reviewed.

Blood Proteins↗

[General cognitive ability. Current state and prospects for further investigations].

The paper reviews general cognitive ability (g), the ways of its measurement, and genetic and behavioural aspects of its investigations. The criteria for assessment of cognitive abilities in animals are also suggested and described. Based on these criteria the new behavioural methods and procedures are developed for investigation of general cognitive ability.

Animals↗

Born to be anxious: neuroendocrine and genetic correlates of trait anxiety in HAB rats.

This review summarises behavioural, neuroendocrine, and genetic characteristics of Wistar rats bred for either high (HAB) or low (LAB) anxiety-related behaviour. Compared to LABs, HAB animals show signs of extreme trait anxiety in a variety of behavioural tests; they further prefer passive coping strategies, indicative of a genetically linked depression-like behaviour, and show signs of increased stress vulnerability. All behavioural parameters associated with trait anxiety are robust and consistent. Resembling psychiatric patients, HAB rats respond to exposure to ethologically relevant stressors with a hyper-reactivity of the hypothalamic-pituitary-adrenal axis and show a pathological outcome of the combined dexamethasone/corticotropin-releasing hormone (Dex/CRH) challenge test. Experimental evidence indicates that over-expression and -release of vasopressin in the hypothalamic paraventricular nucleus is responsible for these behavioural and neuroendocrine phenomena, making the neuropeptide gene a candidate gene of trait anxiety/depression. Indeed, preliminary molecular genetic approaches succeeded in identifying polymorphisms in the promoter structure of the vasopressin gene. This may have implications for understanding the molecular basis for individual variations in trait anxiety and for psychopathology.

Animals↗