Effect Of Yolk Testosterone On Gonadal Testosterone And Aromatase Activity In The Pre-Optic Area Of The Brain In Male Domestic C

Maternal effects are a mother¿s non-genetic contributions to development that alter phenotypic traits in offspring. Maternal effects can take the form of prenatal allocation of resources, such as the deposition of androgens into egg yolks. For example, elevated yolk testosterone increases male sexual behaviors such as copulation solicitation and courtship displays in some avian species, in addition to aggressive behaviors like pecks and intimidating postures towards same-sex competitors. However, the mechanism connecting in ovo testosterone exposure with changes in sexual and aggressive behaviors has yet to be elucidated. While testosterone released by the gonads is important in the activation of sexual behaviors, it must undergo conversion to estrogen by the enzyme aromatase in the pre-optic area (POA) of the avian brain for full expression of sexual activity. POA aromatase is also necessary for the activation of aggressive behaviors in male birds. This experiment tested the hypothesis that elevated yolk testosterone leads to changes in POA aromatase activity and levels of gonadal testosterone, as these two endocrine parameters may mediate the effect of yolk testosterone on the frequency of sexual and aggressive behaviors. The effect of elevated yolk testosterone on gonadal testosterone levels and aromatase activity in the POA of 3-day-old domestic chickens Gallus gallus domesticus was investigated. Unincubated eggs were injected with either 10 ng testosterone in 50 ¿L sesame oil (¿T chicks¿) or 50 ¿L sesame oil (¿C chicks¿). At 3 days post-hatch, gonadal testosterone content was measured after steroid extraction using an EIA, and aromatase activity in the POA was quantified by measuring the production of tritiated water from [1ß-3H]-androstenedione. I predicted that gonadal testosterone levels and brain aromatase activity would be higher in T chicks, however found no difference between treatments. Though juvenile T production peaks at 3 days post-hatch, it is possible that the reproductive systems, including the testes and POA, are not fully developed at this time.

Effect of Participant Gender, Professor Gender, and Activity Interventions on the Understanding of Concepts in Thermodynamics

Misconceptions about heat and temperature have been seen across all educational levels, even in undergraduate engineering courses. One way these misconceptions can be remediated is through instructional methods, such as inquiry-based activities. Performance on assessments in sciences and engineering has been found to vary when gender is taken into consideration. The purpose of the current study was to investigate the effects of participant gender, professor gender, and level of inquiry-based activities on the conceptual understanding of 247 undergraduate engineering students in thermodynamics. A pre-test post-test design was used. Conceptual understanding of thermodynamics was measured by students’ scores on the Concept Inventory for Engineering Thermodynamics (CIET; Vigeant, Prince & Nottis, 2011). Inquiry-based activities were developed by the researchers and given to professors who determined if they would do all, some, or none of them as they taught. Significant differences were found among participants of different gender, different gender of the professor instructing the course, and level of inquiry-based activity. The participants who were exposed to all of the activities provided didsignificantly better on the post-test than those who were only exposed to some or none of the activities. The results from this current study indicated that differences in gender, professorgender, and level of inquiry-based activity has an effect on undergraduate engineering students’ conceptual understanding of thermodynamics. Future research should investigate more factorsthat contribute to lower representation of women in the engineering field.