DOI: 10.5061/dryad.kprr4xhbk
title: Data from: Avian offspring prenatal DNA methylation response to maternal corticosterone dosing during reproduction

description: 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 spectrometry (LC-MS) and methylation-sensitive
 amplification fragment length polymorphism (MS-AFLP). LC-MS analysis
 showed that global DNA methylation was lower in embryos from CORT-treated
 mothers, compared to control embryos. In contrast, blood vessel DNA from
 eggs from CORT-treated mothers showed global methylation increases,
 compared to control samples. There was a higher proportion of global DNA
 methylation in the embryonic DNA of second clutches, compared to first
 clutches. Locus-specific analyses using MS-AFLP did not reveal a treatment
 effect. Our results indicate that an acute elevation of maternal CORT
 around ovulation impacts DNA methylation patterns in their offspring. This
 could provide a mechanistic understanding of how a mother’s experience can
 affect her offspring’s phenotype.
description: Australian Zebra finches (<em>Taeniopygia
 castanotis</em>) 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).
description: # 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, clutch size (number of
 eggs laid in each clutch) * Dates (in dd/mm/yyyy format) for: nest
 material provided; nest building initiated; clutch initiated; first egg in
 clutch laid; and date focal egg laid * Lay latency (in whole days):
 between material provided date and first egg laid; and, between nest build
 initiation date and first egg laid 3\) Egg (vitelline) blood vessel (from
 eggs with 5 days of incubation) DNA methylation assessed via MS-AFLP *
 Absence/ presence for: Allele number (columns G-GH); DNA fragment length
 (columns GI-NJ); and peak height (columns NK-UL). * Restriction enzyme
 used to assess DNA methylation (HpaII or MspI) * Treatment group of mother
 (treatment: mothers remotely orally dosed with CORT daily; control:
 mothers remotely dosed with the oil vehicle, only, daily) * Maternal ID
 (also a proxy for parental pair ID, or familial group, as females were
 paired with the same male throughout all reproduction) * Clutch number
 (first or second clutch for each pair) * Egg number (order in the clutch
 each egg was laid)