Avian offspring prenatal DNA methylation response to maternal corticosterone dosing during reproduction

Avian embryos develop in an egg composition which reflects both maternal condition and the recent environment of their mother. In birds, yolk corticosterone (CORT) influences development by impacting pre- and postnatal growth, as well as nestling stress responses and development. One possible mechanism through which maternal CORT may affect offspring development is via changes to offspring DNA methylation. We sought to investigate this, for the first time in birds, by quantifying the impact of manipulations to maternal CORT on offspring DNA methylation. We non-invasively manipulated plasma CORT concentrations of egg-laying female zebra finches (Taeniopygia castanotis) with an acute dose of CORT administered around the time of ovulation and collected their eggs. We then assessed DNA methylation in the resulting embryonic tissue and in their associated vitelline membrane blood vessels, during early development (5 days after lay), using two established methods - liquid chromatography–mass ..., Australian Zebra finches (Taeniopygia castanotis) were bred in a laboratory setting. Treatment group females were orally dosed with corticosterone throughout breeding and reproduction (control females instead orally dosed with the oil vehicle, alone). Females were bred twice (with the same mate), once under treatment, once under control (half treatment first, half control first). Eggs were collected on the day of lay and artificially incubated for 5 days of development, then collected and immediately frozen. DNA from the egg was purified from both embryos and vitelline membrane blood vessels. The extracted DNA was hydrolysed and processed via mass spectrometry (LC-MS). Separately, the extracted DNA from the egg (vitelline) blood vessels was processed via enzymatic DNA profiling (MS-AFLP) and sent to AGRF for analysis (single base resolution of DNA fragments). The data was analysed with R (via RStudio) using packages nlme (LC-MS data) and msap (MS-AFLP data)., , # Avian offspring prenatal DNA methylation response to maternal corticosterone dosing during reproduction

## Description of the data files

1\) Embryo (5 days of incubation) DNA methylation assessed via LC-MS

* Ratio of 5mdC (methylated cytosine) to guanosine for embryos (incubated to 5 days development)

2\) Egg (vitelline) blood vessel (from eggs with 5 days of incubation) DNA methylation assessed via LC-MS

* Ratio of 5mdC (methylated cytosine) to guanosine for egg (vitelline) blood vessels (from eggs incubated to 5 days development)

Both data sets (1 & 2) also include the following metrics:

* Treatment group of mother (treatment: mothers remotely orally dosed with CORT daily; control: mothers remotely dosed with the oil vehicle, only, daily)
* Mass in (g) of: mother finches (pre- and post- reproduction) and whole eggs (on day of lay, pre-incubation)
* Length in (mm) of maternal tarsi
* Clutch number (1st or 2nd); egg number (order laid in each clutch); and, clu...