Kristen J. Navara
Research Interests
My research is integrative and multidisciplinary in that it combines the fields of endocrinology, immunology, and molecular biology to answer broad evolutionary and ecological questions. My primary interest lies in maternal effects, particularly how females can modify the phenotype of offspring prior to parturition or hatch. Specific interests include the mechanisms underlying sex ratio manipulation by female birds and mammals and the deposition of yolk hormones by female birds.
Ongoing research projects include:
Mechanisms of sex ratio adjustment in birds
Avian mothers have the unique ability to alter the sexes of the offspring they produce in response to changing environmental and social conditions. Our research suggests that the heterogametic female birds can manipulate offspring sex at the chromosomal level, by influencing which sex chromosome is retained in the ovulated oocyte and which is discarded. We are currently working to determine the molecular mechanisms by which this occurs. Ultimately we hope to develop a treatment by which sexes can be purposefully manipulated for use in the poultry industry.
Avian mothers have the unique ability to alter the sexes of the offspring they produce in response to changing environmental and social conditions. Our research suggests that the heterogametic female birds can manipulate offspring sex at the chromosomal level, by influencing which sex chromosome is retained in the ovulated oocyte and which is discarded. We are currently working to determine the molecular mechanisms by which this occurs. Ultimately we hope to develop a treatment by which sexes can be purposefully manipulated for use in the poultry industry.
Epigenetic maternal programming in birds
In most cases, after fertilization takes place, it is up to the female to prepare the developing embryo for the environment into which it will hatch. While placental mammals have constant contact and communication with embryos during development, birds are separated from offspring by the eggshell and can only direct development via the substances deposited into eggs prior to ovulation. We are examining how female birds can use yolk hormones to alter offspring DNA in an epigenetic manner to permanently program offfspring physiology and behavior.
Control of natal sex ratios in humans
Birds are not the only ones that have the ability to influence offspring sex ratios according to surrounding conditions. Mammals can also bias sex ratios, and humans are no exception. Sex ratio biases have been documented in humans in response to a plethora of variables. We have found that humans a tropical latitudes produce significantly more girls. In current work, we are focusing on the influences of gestational weight gain on offspring sex..