Derivation of es Cells From Early Stage Preimplantation Embryos and Characterisation of their Cardiac Differentiation Potential in Mice.

Most murine embryonic stem cell lines have been derived from the inner cell mass of blastocysts and extensively studied in different aspects including generation of organ specific cells. However, no detailed studies have been made on cardiac specific gene expression, immunocytochemical and electrophysiological characterisation of cardiomyocytes generated from early stage (preimplantation) embryo derived embryonic stem cells in mice. In the present study, new embryonic stem cell lines were derived from early stage preimplanatation embryos in mice. In vitro differentiation of such cell lines readily generated cardiomyocytes, which expressed different cardiac specific genes in a temporally regulated manner as well as cardiac cells specific proteins. This is probably the first report, which showed the temporal pattern of cardiac specific genes as well as protein expression in cardiac cells generated from in vitro differentiation of preimplantation embryo derived ES cells.

Examining a pathway for hormone mediated maternal effects--yolk testosterone affects androgen receptor expression and endogenous testosterone production in young chicks (Gallus gallus domesticus).

In vertebrates maternal androgens can substantially influence developing offspring, inducing both short and long term changes in physiology and behavior, including androgen sensitive traits. However, how the effects of maternal hormones are mediated remains unknown. Two possible pathways are that maternal androgens affect parts of the hypothalamus-pituitary-gonadal axis (HPG axis) or the sensitivity to androgens by affecting androgen receptor (AR) densities within the brain. To investigate both pathways, testosterone within the physiological range or vehicle only was injected into the egg yolk of unincubated chicken eggs and AR mRNA expression in different brain nuclei as well as plasma testosterone levels were measured in two week old male and female chicks that had hatched from these eggs. Our results showed a significant sex difference in plasma testosterone levels with males showing higher levels than females. Furthermore, AR mRNA expression as well as plasma testosterone levels were significantly lower in chicks hatched from testosterone treated eggs. These results suggest a compensatory mechanism for avoiding potential detrimental effects of high testosterone levels.

Epigenesis of behavioural lateralization in humans and other animals.

Despite several decades of research, the epigenesis of behavioural and brain lateralization is still elusive, although its knowledge is important in understanding developmental plasticity, function and evolution of lateralization, and its relationship with developmental disorders. Over the last decades, it has become clear that behavioural lateralization is not restricted to humans, but a fundamental principle in the organization of behaviour in vertebrates. This has opened the possibility of extending descriptive studies on human lateralization with descriptive and experimental studies on other vertebrate species. In this review, we therefore explore the evidence for the role of genes and environment on behavioural lateralization in humans and other animals. First, we discuss the predominant genetic models for human handedness, and conclude that their explanatory power alone is not sufficient, leaving, together with ambiguous results from adoption studies and selection experiments in animals, ample opportunity for a role of environmental factors. Next, we discuss the potential influence of such factors, including perinatal asymmetrical perception induced by asymmetrical head position or parental care, and social modulation, both in humans and other vertebrates, presenting some evidence from our own work on the domestic chick. We conclude that both perinatal asymmetrical perception and later social modulation are likely candidates in influencing the degree or strength of lateralization in both humans and other vertebrates. However, in most cases unequivocal evidence for this is lacking and we will point out further avenues for research.