Tezak, Boris

Marine turtles exhibit temperature-dependent sex determination (TSD). During critical periods of
embryonic development, the nest’s thermal environment directs whether an embryo will develop as a
male or a female. At warmer sand temperatures the nest tends to produce female-biased sex ratios.
The rapid increase of global temperature highlights the need for a clear assessment of effects on sea
turtle sex ratios. However, identifying hatchling sex ratios at rookeries remain coarse estimates due to
the lack of any external gender markers. We rely mainly upon laparoscopic procedures to verify a
hatchling sex; however, in some species, morphological sex can be ambiguous even at the histological
level. Recent studies using immunohistochemical techniques identified that red-eared slider
(Trachemys scripta) embryos over-expressed a particular cold-induced RNA binding protein in the
ovaries in comparison to the testes. This principle allows the distinction between females and males.
We developed a variation of this technique and successfully identified the sexes of loggerhead sea
turtle (Caretta caretta) hatchlings, as confirmed by standard histological and laparoscopic methods that
reliably identifies the sex in this species. Next, we tested a more challenging species, the leatherback
turtle (Dermochelys coriacea), which retains many neotenic features. The morphology of leatherback
hatchling gonads remains difficult to interpret, particularly when dead-in-nest hatchlings and embryos
are the source tissues. In summary, this new and more efficient technique enhances our ability to investigate and identify baseline hatchling sex ratios, a critical progression in assessing global climate
change on sea turtle populations.

The 3MT® competition celebrates the exciting research conducted by graduate students. Developed by The University of Queensland (UQ), the exercise cultivates students’ academic, presentation, and research communication skills. The competition supports their capacity to effectively explain their research in three minutes, in language appropriate to a non-specialist audience. The first 3MT® competition was held at the University of Queensland in 2008 with 160 students competing. In 2009 and 2010 the 3MT® competition was promoted to other Australian and New Zealand universities and enthusiasm for the concept grew. Since 2011, the popularity of the competition has increased and 3MT® competitions are now held in over 170 universities across more than 18 countries worldwide.