Browsing by Author "Pennonen, Jana"

Puberty is a process of physiological changes, through which an immature individual becomes sexually mature. In humans, timing of puberty is highly variable within and between sexes and populations. Timing of puberty represents a complex trait, which is controlled both genetically and environmentally. Precocious pubertal timing is associated with development of metabolic diseases later in life, such as obesity and diabetes, and other disorders as ovarian and testicular cancer. Despite the estimated high heritability (50-80%) of pubertal timing, its genetic background is still poorly understood. Recently, the genome-wide association studies (GWASs) revealed many novel pubertal timing associated loci. Nevertheless, molecular mechanisms behind these associations remain elusive. This thesis focused on gene vestigial-like family member 3 (VGLL3), which is associated with pubertal timing in humans and maturation in Atlantic salmon (Salmo salar). Since the main physical structures, such as the hypothalamus and the pituitary gland, needed in reaching puberty are evolutionary conserved and start to develop in vertebrates during embryogenesis, the aim was to study the expression pat-terns and role of vgll3 in zebrafish (Danio rerio) during this period. In order to localize expression patterns of the vgll3 gene in zebrafish embryos, a whole-mount in situ RNA hybridization (ISH) was performed. mRNA overexpression and morpholino oligonucleotide (MO) knockdown techniques were used to alter the vgll3 gene expression levels in 0-5 dpf zebrafish. The combined injections of both mRNA and MO were performed to validate MO specificity. The ISH experiment showed the expression patterns in 0-1 dpf embryos. The expression was ubiquitous up to 6 hours post fertilization becoming more localized to specific regions in the head and trunk of the embryos during the later stages. Altering vgll3 expression with high concentrations of synthetic mRNA or MO lead to phenotypical abnormalities such as shortened and curved body axis, pericardial and yolk sack edemas, deformed heads and eyes. However, it remained unclear if these malformations appear only due to the alteration of vgll3 expression levels. The results suggest that vgll3 may play an important role in the embryonic development. However, the study does not show that vgll3 has impacts on the pubertal timing in vertebrates by affecting the development of the structures required for sexual maturation.