Molecular investigations on sex determination and differentiation pathways in the common carp, Cyprinus carpio

摘要: Common carp is a highly important species, with significant aquaculture production and frequent use for fish biology and research. In Australia, New Zealand the US, common are declared as an invasive pest causing damage to endemic ecosystems. This thesis aims to advance our understanding of the molecular pathway sex determination differentiation in a view facilitate development genetic control mechanisms this species. The objective was addressed by molecular cloning six key genes involved sexual development, 3 each critical female male development. Spatial expression of these analysed adult tissues onset timing was determined during early ontogeny through larval at two temperatures (20 25 °C) allowing investigation effect temperature on expression final ratios. The study confirms that there two isoforms cytochrome P450 aromatase gene namely ovarian (cyp19a) brain (cyp19b). Based on the level CYP19 expression, found be main site aromatase synthesis, contributed predominantly isoform. Also expressed in the were both SRY (sex-determining region Y)-box 9 (sox9) and forkhead box L2 (foxL2). Within gonad, cyp19a foxL2 predominantly expressed ovary while doublesex mab-3 related transcription factor 1 (dmrt1) primarily testis. Ontogenic indicated that cyp19a sox9a maternally inherited. Female showed sexually dimorphic only larger than 20 mm, warmer conditions (25 °C) suppressing suggesting male-skewed ratio. indicates that differential maybe result rather cause. Conversely, cyp19b peaked prior hatching possibly indicating that sexual occurs first brain, before gonads present. Expression dmrt1, development, soon after fertilisation °C treatment role sex-determining pathway. Peak expression sox9 occurred hatch, consequent expression failing show any sexually dimorphic these genes play but not sex differentiation. This dmrt1 accurate markers either or testis differentiation respectively. The ability influence these genes may manipulation ratios carp, other fish. would be benefit control, where population bias can extinction, and also aquaculture, monosex populations improve production efficiency. By developing greater differentiation teleost it possible gain further insights into evolution sex determination all vertebrate