Behavior Genetics and Post Genomics

The science of genetics is undergoing a paradigm shift. Recent discoveries, including the activity of retrotransposons, the extent of copy number variations, somatic and chromosomal mosaicism, and the nature of the epigenome as a regulator of DNA expressivity, are challenging a series of dogmas concerning the nature of the genome and the relationship between genotype and phenotype. DNA, once held to be the unchanging template of heredity, now appears subject to a good deal of environmental change; considered to be identical in all cells and tissues of the body, there is growing evidence that somatic mosaicism is the normal human condition; and treated as the sole biological agent of heritability, we now know that the epigenome, which regulates gene expressivity, can be inherited via the germline. These developments are particularly significant for behavior genetics for at least three reasons: First, these phenomena appear to be particularly prevalent in the human brain, and likely are involved in much of human behavior; second, they have important implications for the validity of heritability and gene association studies, the methodologies that largely define the discipline of behavior genetics; and third, they appear to play a critical role in development during the perinatal period, and in enabling phenotypic plasticity in offspring in particular. I examine one of the central claims to emerge from the use of heritability studies in the behavioral sciences, the principle of “minimal shared maternal effects,” in light of the growing awareness that the maternal perinatal environment is a critical venue for the exercise of adaptive phenotypic plasticity. This consideration has important implications for both developmental and evolutionary biology

Behavioural Genetics in the Postgenomics Era

There is growing evidence that the complexity of higher organisms does not correlate with the ‘complexity’ of the genome (the human genome contains fewer protein coding genes than corn, and many genes are preserved across species). Rather, complexity is associated with the complexity of the pathways and processes whereby the cell utilises the deoxyribonucleic acid molecule, and much else, in the process of phenotype formation. These pro- cesses include the activity of the epigenome, noncoding ribonucleic acids, alternative splicing and post-transla- tional modifications. Not accidentally, all of these pro- cesses appear to be of particular importance for the human brain, the most complex organ in nature. Because these processes can be highly environmentally reactive, they are a key to understanding behavioural plasticity and highlight the importance of the developmental process in explaining behavioural outcomes.

(Table 2) Age determination of harp seals (Pagophilus groenlandicus) from the Barents Sea - comparison of methods

Lower jaws (containing the teeth), eyes, and skin samples were collected from harp seals (Pagophilus groenlandicus) in the southeastern Barents Sea for the purpose of comparing age estimates obtained by 3 different methods, the traditional technique of counting growth layer groups (GLGs) in teeth and 2 novel approaches, aspartic acid racemization (AAR) in eye lens nuclei and telomere sequence analyses as a proxy for telomere length. A significant correlation between age estimates obtained using GLGs and AAR was found, whereas no correlation was found between GLGs and telomere length. An AAR rate (k Asp) of 0.00130/year ± 0.00005 SE and a D-enantiomer to L-enantiomer ratio at birth (D/L 0 value) of 0.01933 ± 0.00048 SE were estimated by regression of D/L ratios against GLG ages from 25 animals (12 selected teeth that had high readability and 13 known-aged animals). AAR could prove to be useful, particularly for ageing older animals in species such as harp seals where difficulties in counting GLGs tend to increase with age. Age estimation by telomere length did not show any correlation with GLG ages and is not recommended for harp seals.

UPTAKE OF THE PERIODIC HEALTH EXAM AMONG ADULTS WITH INTELLECTUAL AND DEVELOPMENTAL DISABILITIES FROM 2003 TO 2015

Background: Over the past decade, annual heath exams have been de-emphasized for the general population but emphasized for adults with intellectual and developmental disabilities (IDD). The purpose of this project was to determine if there has been an increase in the uptake of the health exam among adults with IDD in Ontario, to what extent, and the effect on the quality of preventive care provided. Methods: Using administrative health data, the proportion of adults (18-64 years old) with IDD who received a health exam (long appointment, general assessment, and “true” health exam), a high value on the primary care quality composite score (PCQS), and a health exam or high PCQS each year was compared to the proportion in a propensity score matched sample of the general population. Negative binomial and segmented negative binomial regression controlling for age and sex were used to determine the relative risk of having a health exam/high PCQS/health exam or PCQS over time. Results: Pre joinpoint, the long appointment and general assessment health exam definitions saw a decrease and the “true” health exam saw an increase in the likelihood of adults having a health exam. Post joinpoint, all health exam definitions saw a decrease in the likelihood of adults having a health exam. Pre joinpoint, all PCQS measures (high PCQS, long appointment or high PCQS, “true” health exam or high PCQS) saw an increase in the likelihood for adults to achieve a high PCQS or high PCQS/have a health exam. Post joinpoint, all PCQS measures saw a decrease in the likelihood for adults to achieve a high PCQS or high PCQS/have a health exam. Achieving a high PCQS was strongly associated with having a health exam regardless of health exam definition or IDD status. Conclusions: Despite the publication of guidelines, only a small proportion of adults with IDD are receiving health exams. This indicates that the publication of guidelines alone was not sufficient to change practice. More targeted measures, such as the implementation of an IDD-specific health exam fee code, should be considered to increase the uptake of the health exam among adults with IDD.

The genetic basis of psychological traits in infancy: Implications for understanding the causes of developmental psychopathology

This chapter reviews genetic studies that have aimed to identify genes influencing psychological traits in infancy (from birth to age 12 months), and considers how this research informs us about the causes of developmental psychopathology. Specifically, this chapter systematically reviews findings from studies that associated common genetic variants with individual variation in infants’ attention, temperament and behaviour, and attachment disorganisation. DRD4 and 5-HTTLPR genes were the most frequently studied candidate genes. Possibly the most coherent set of results relates to the L-DRD4 genotype, which is significantly associated with infant attention, temperament, and attachment style. Research in infant genetics has been strengthened by a careful focus on uniform age ranges within studies, by several longitudinal studies, and by exploration of gene-environment interactions between genes and maternal characteristics. However there is also considerable inconsistency in results in this field and possible reasons for this are discussed. The chapter outlines the main genetic methods that have been used and what new genetic approaches such as polygenic risk scoring could offer infant genetics. Recent findings suggest that some traits during infancy predict individual differences in developmental psychopathology in childhood. It is argued that infant genetic research has considerable potential for the identification of populations at risk for psychopathology in later life, and this remains an area open for future research.

Stratégies reproductives et sex-ratio chez le termite Cavitermes tuberosus (Emerson, 1925) -- Biologie des Organismes et Ecologie

Recently shown in some termites, Asexual Queen Succession (AQS) is a reproductive strategy in which the primary queen is replaced by numerous parthenogenetically-produced neotenic queens that mate with the primary king. In contrast, the workforce and alate dispersers are produced sexually. If the primary king is replaced by a sexually-produced neotenic son, the matings between neotenic male and females beget asymmetries in the reproductive value of alates, promoting a female-biased alate sex-ratio. Cavitermes tuberosus (Termitidae: Termitinae) is a soil-feeding tropical species, which shows parthenogenetically-produced neotenics and an AQS syndrome. Our work aims to characterize the reproductive strategies in this species by determining (i) the developmental scheme, (ii) the genetic origin of sexuals, (iii) the level of genetic structure (analysis of 65 nests distributed in 14 sites) and (iv) the alate sex-ratio.Our results show that (i) neotenic females develop from the third or fourth nymphal instar; (ii) the majority of neotenic females (82%) are parthenogenetically-produced while only 2% of female alates are so; (iii) nests are differentiated within sites, indicating that the foundation of new nests mainly occurs by nuptial flights; (iv) numerical sex-ratio of alate-destined sexuals is balanced (SRN=0.509, IC95%=0.497-0.522) while investment sex-ratio is slightly female-biased (SRE=0.529, IC95%=0.517-0.542). Altogether, our results demonstrate AQS and its implications in C. tuberosus, and reveal particularities compared to other species in which AQS has been demonstrated: neotenic-headed nests are less frequent than primary-headed ones and neotenic females never become physogastric. AQS is found in various ecological contexts and seems phylogenetically more widespread than previously thought. This strategy shows some evolutionary advantages but these seem to differ depending on species.

Toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the developing male Wistar(Han) rat II: chronic dosing causes developmental delay

We have investigated whether fetal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes defects in the male reproductive system of the rat, using chronically exposed rats to ensure continuous exposure of the fetus. 5-6 week old rats were exposed to control diet, or diet containing TCDD, to attain an average dose of 2.4, 8 and 46 ng TCDD kg-1 day-1 for twelve weeks, whereupon the rats were mated, and allowed to litter; rats were switched to control diet after parturition. Male offspring were allowed to develop until kills on PND70 (25 per group), or PND120 (all remaining animals). Offspring from the high dose group showed an increase in total litter loss, and the number of animals alive on post-natal day (PND) 4 in the high dose group was ~26% less than control. The high and medium dose offspring showed decreased weights at various ages. Balano-preputial separation was significantly delayed in all three dose groups, compared to control. There were no significant effects of maternal treatment when the offspring were subjected to a functional observational battery, or learning tests, with the exception that the high dose group showed a deficit in motor activity. 20 rats per group were mated to females, and there were no significant effects of maternal treatment on the fertility of these rats, nor on the F1 or F2 sex ratio. Sperm parameters at PND70 and 120 showed no significant effect of maternal treatment, with the exception that there was an increase in the proportion of abnormal sperm in the high dose group at PND70; this is associated with the developmental delay in puberty in this dose group. There were no remarkable findings of maternal treatment on organ weights, with the exception that testis weights were reduced by ~10% at PND70 (but not PND120), and although the experiment was sufficiently powered to detect small changes, ventral prostate weight was not reduced. There were no significant effects of maternal treatment upon histopathological comparison of high dose and control group organs. These data confirm that developmental exposure to TCDD shows no potent effect on adult sperm parameters or accessory sexual organs, but show that delay in BPS occurs after exposure to low doses of TCDD, and this is dependent upon whether TCDD is administered acutely or chronically.

Rare sex or out of reach equilibrium? The dynamics of F-IS in partially clonal organisms

Background: Partially clonal organisms are very common in nature, yet the influence of partial asexuality on the temporal dynamics of genetic diversity remains poorly understood. Mathematical models accounting for clonality predict deviations only for extremely rare sex and only towards mean inbreeding coefficient (F-IS) over bar < 0. Yet in partially clonal species, both F-IS < 0 and F-IS > 0 are frequently observed also in populations where there is evidence for a significant amount of sexual reproduction. Here, we studied the joint effects of partial clonality, mutation and genetic drift with a state-and-time discrete Markov chain model to describe the dynamics of F-IS over time under increasing rates of clonality. Results: Results of the mathematical model and simulations show that partial clonality slows down the asymptotic convergence to F-IS = 0. Thus, although clonality alone does not lead to departures from Hardy-Weinberg expectations once reached the final equilibrium state, both negative and positive F-IS values can arise transiently even at intermediate rates of clonality. More importantly, such "transient" departures from Hardy Weinberg proportions may last long as clonality tunes up the temporal variation of F-IS and reduces its rate of change over time, leading to a hyperbolic increase of the maximal time needed to reach the final mean (F-IS,F-infinity) over bar value expected at equilibrium. Conclusion: Our results argue for a dynamical interpretation of F-IS in clonal populations. Negative values cannot be interpreted as unequivocal evidence for extremely scarce sex but also as intermediate rates of clonality in finite populations. Complementary observations (e.g. frequency distribution of multiloci genotypes, population history) or time series data may help to discriminate between different possible conclusions on the extent of clonality when mean (F-IS) over bar values deviating from zero and/or a large variation of F-IS over loci are observed.

Developmental mechanisms of stripe patterns in rodents

International audience

Romantic relationships and adjustment in early adulthood: The role of cross-sex experience in the context of social norms and support

Attachment and interpersonal theory suggest a sequential pattern of relationships beginning in the earliest stage of development and progressing to social and eventually romantic relationships. Theoretically, cross-sex experiences have an important role in the progression of interpersonal relationships. Despite the prevalence of these theories about the nature of romantic relationship development, the linkage of cross-sex experience (CSE) to romantic relationships has not been established. Indeed, it is an intuitive assumption, especially within Western society and these theories do not consider socio-cultural factors that may influence CSE and relationship satisfaction. This study addresses the varying contextual factors that may contribute to relationship satisfaction and adjustment, aside from CSE, and is divided into two parts. Study 1, addresses CSE, relationship satisfaction, and adjustment in a unique population, ultra-Orthodox Jews. Among this population, social or romantic CSE is limited and sexes are effectively segregated. Study 2, expanded the study to a larger sample of U.S. college students, to assess the linkage of CSE to romantic relationship satisfaction in a more typical Western population. It included social norm and support variables to address the contextual nature of relationship development and satisfaction. Results demonstrated clear differences in the relation between CSE and relationship satisfaction in the two samples. In the first sample CSE was unrelated to relationship satisfaction; nevertheless, relationship satisfaction was associated with adjustment as it is for more typical populations with greater CSE. These results suggested the importance of specifying how social norms and social support relate to CSE, relationship satisfaction and adjustment. The results from the second sample were consistent with the theoretical framework upon which the social/romantic literature is based. CSE was directly connected to relationship satisfaction. As anticipated, CSE, relationship satisfaction, and adjustment also varied as a function of social norms and support. These findings further validate the influence of socio-cultural factors on relationship satisfaction and adjustment. This study contributes to the romantic relationship literature and broadens our understanding of the complex nature of interpersonal and romantic relationships.^

Developmental, relational and situational characteristics of maritally abusive men

Rapport de stage présenté à la Faculté des Arts et Sciences en vue de l’obtention du grade de Maître des Sciences (M. Sc.) en Criminologie, Option Stage en Intervention

Developmental and physical-fitness associations with gross motor coordination problems in peruvian children

he aims of this cross-sectional study were to examine the developmental characteristics (biological maturation and body size) associated with gross motor coordination problems in 5193 Peruvian children (2787 girls) aged 6–14 years from different geographical locations, and to investigate how the probability that children suffer with gross motor coordination problems varies with physical fitness. Children with gross motor coordination problems were more likely to have lower flexibility and explosive strength levels, having adjusted for age, sex, maturation and study site. Older children were more likely to suffer from gross motor coordination problems, as were those with greater body mass index. However, more mature children were less likely to have gross motor coordination problems, although children who live at sea level or at high altitude were more likely to suffer from gross motor coordination problems than children living in the jungle. Our results provide evidence that children and adolescents with lower physical fitness are more likely to have gross motor coordination difficulties. The identification of youths with gross motor coordination problems and providing them with effective intervention programs is an important priority in order to overcome such developmental problems, and help to improve their general health status.

Developmental, relational and situational characteristics of maritally abusive men

Rapport de stage présenté à la Faculté des Arts et Sciences en vue de l’obtention du grade de Maître des Sciences (M. Sc.) en Criminologie, Option Stage en Intervention