Proteomic insight into human directed selection of the domesticated chicken Gallus gallus

Abstract

Chicken domestication began at least 3,500 years ago for purposes of divination, cockfighting, and food. Prior to industrial scale chicken production, domestication selected larger birds with increased egg production. In the mid-20th century companies began intensive selection with the broiler (meat) industry focusing on improved feed conversion, rapid growth, and breast muscle yield. Here we present proteomic analysis comparing the modern broiler line, Ross 708, with the UIUC legacy line which is not selected for growth traits. Breast muscle proteome analysis identifies cellular processes that have responded to human directed artificial selection. Mass spectrometry was used to identify protein level differences in the breast muscle of 6-day old chicks from Modern and Legacy lines. Our results indicate elevated levels of stress proteins, ribosomal proteins and proteins that participate in the innate immune pathway in the Modern chickens. Furthermore, the comparative analyses indicated expression differences for proteins involved in multiple biochemical pathways. In particular, the Modern line had elevated levels of proteins affecting the pentose phosphate pathway, TCA cycle and fatty acid oxidation while proteins involved in the first phase of glycolysis were reduced compared to the Legacy line. These analyses provide hypotheses linking the morphometric changes driven by human directed selection to biochemical pathways. These results also have implications for the poultry industry, specifically Wooden Breast disease which is linked to rapid breast muscle growth.

Fig 1. Results of artificial selection for increased feed efficiency and breast muscle yield.

Comparison of 35-day old male UIUC legacy chicken (left) with a 35-day old male Ross 708 chicken (right). The UIUC bird is typical in size and shape for a chicken from the 1950s while the Ross 708 bird is from a modern commercial flock grown for human consumption.

Fig 2. Gene ontology results.

Orange hexagons refer to GO terms and rectangles refer to proteins differentially enriched between modern (Red) and legacy (Green) chicken muscle.

Fig 3. Glycolysis, pentose phosphate pathway and TCA cycle.

Red rectangles indicate enzymes enriched in the modern line while dark green indicates the enzymes enriched in the legacy line.

Fig 4. Beta-oxidation of Saturated Fatty Acids (SFA) and Unsaturated Fatty acids (USFA).

The step indicated by the oval is repeated, sequentially removing acetyl-CoA, until the 12 carbon Lauroyl-CoA is oxidized to the 4 carbon acetoacetyl-CoA which is oxidized to Acetyl-CoA by ACAT2. Red rectangles indicate enzymes enriched in the modern line.