Project description:Here we show the potential of proteins preserved in Pleistocene eggshell for addressing a longstanding controversy in human and evolution: the identity of the extinct bird that laid the eggs which were exploited by Australia’s first inhabitants. The eggs had been originally attributed to the iconic extinct flightless Genyornis newtoni, and subsequently dated to before 50 ±5 ka by Miller et al. (2016). This was taken to represent the extinction date for this endemic megafaunal species and thus implied a role of humans in its demise. A contrasting hypothesis, according to which the eggshell was laid by a large megapode (mound-builder), would therefore acquit humans of their responsibility in the extinction of Genyornis. Ancient protein sequences were reconstructed and used to assess the evolutionary proximity of the undetermined eggshell to extant birds, rejecting the megapode hypothesis. Ancient DNA could not be retrieved from these highly degraded samples, but morphometric data supported the attribution of the eggshell to Genyornis. When used in triangulation to address well-defined hypotheses, palaeoproteomics is a precious tool for reconstructing the evolutionary history of extinct and extant species. Here we show that the identification of Genyornis eggshell implies a more nuanced understanding of the modes of interactions between humans and their environment.

2022-07-19 | PXD027713 | Pride

Heterochronic activation of TGF-β signaling drives the diversity of the avian sterna

Project description:Adaptive evolution has driven the diversification of vertebrate skeletal morphology, enabling a wide array of locomotor modes and lifestyles. In volant birds (carinates), the sternum develops a ventral keel that provides an attachment site for massive pectoral muscles essential for powered flight. In contrast, flightless ratites have lost both flight capability and the keel, resulting in a striking morphological contrast between their sterna. Here, we interrogated the cellular and molecular basis underlying this morphological divergence by using chicken embryos as a carinate model and emu embryos as a ratite model. Through a series of analyses including spatiotemporal transcriptomics and a spheroid culture system, we found that TGF-β signaling, which promotes proliferation of ventral sternal chondroprogenitors, is activated in both species until the stage when the left and right sternal progenitors meet; however, in chicken this activation persists beyond this stage, driving ventral extension of the keel primordium, whereas in emu it shuts off early, culminating in the absence of a protruding keel. Together, our findings suggest that skeletal morphological changes associated with behavioral transitions can arise from heterochrony in developmental signaling, thereby deepening our understanding of the evolutionary logic shaping skeletal diversification.

2026-04-01 | GSE313054 | GEO

Stranded mRNA sequencing of chicken cecal tissue

Project description:The objective of this study was to determine if Salmonella colonization of chickens could be reduced through competitive exclusion using a defined community of chicken commensal bacteria. One-day old White Leghorn chicks, hatched on-site, were randomly divided into experimental groups and given an oral gavage of either a defined community of 15 bacterial species (DC), cecal contents (CC), or sterile PBS (control; CT). After one week, birds were euthanized for cecal content collection (pre-Salmonella sample) while the remaining birds were orally gavaged 1 X 10^8 colony forming units (CFU) of Salmonella enterica ser. Heidelberg strain 2813 (SH2813). Bacterial counts for three post-Salmonella timepoints (3, 14, and 28 days post inoculation; dpi) were evaluated. Bacteriological enumeration was performed by plating cecal contents onto Salmonella selective agar to determine CFU/g in each group for all collection days. Cecal contents were also used for 16S amplicon sequencing. Cecal tissue was used for stranded mRNA sequencing (RNA-Seq).

2026-01-30 | GSE286977 | GEO

The phylogenetic significance of the morphology of the syrinx, hyoid and larynx, of the southern cassowary, Casuarius casuarius (Aves, Palaeognathae).

Project description: Not available

| S-EPMC6935130 | biostudies-literature