Characterization of the intronic VNTR polymorphisms found in a paralog of chicken serotonin transporter gene

• Published in: Animal science journal Vol. 84; no. 4; pp. 281 - 288
• Main Authors: Abe, Hideaki, Takeuchi, Hiro-aki, Yamada, Satoko, Nakamura, Akihiro, Nagao, Kenji, Nirasawa, Keijiro, Ito, Shin'ichi, Inoue-Murayama, Miho
• Format: Journal Article
• Language: English
• Published: Australia Blackwell Publishing Ltd 01.04.2013
• Subjects: Animals; Binding Sites; Breeding; CCCTC-binding factor (CTCF); Chickens - genetics; Genes; Genotype; Impulsive Behavior - genetics; Introns; Male; Minisatellite Repeats - genetics; Neurotransmitters; paralog; Phenotype; Polymerase Chain Reaction; Polymorphism; Polymorphism, Genetic; Serotonin; Serotonin Plasma Membrane Transport Proteins - genetics; serotonin transporter gene (5-HTT); Tandem Repeat Sequences; Transcription, Genetic; variable number of tandem repeat (VNTR)
• ISSN: 1344-3941; 1740-0929
• DOI: 10.1111/asj.12011

Polymorphisms in the neurotransmitter‐related genes can be a major source of behavioral variations. We searched for polymorphic sites in chicken neurotransmitter‐related genes and identified two variable number of tandem repeat (VNTR) loci encompassing the paralog of chicken serotonin transporter gene (5‐HTT). Both intronic VNTR were highly polymorphic across chicken breeds and the other Galliformes species, even though predominant alleles were considerably different among breeds. One VNTR locus contained sequences complementary to a conserved motif of CCCTC‐binding factor (CTCF) within each repetitive unit, indicating that transcription of chicken 5‐HTT paralog may be regulated by the CTCF protein. It is of great interest to contrast these results with previous knowledge on the human 5‐HTT that also has CTCF binding sites in the repetitive units of intronic VNTR. Additionally, we measured the degree of impulsiveness in domestic chicks for their preference of immediate/small to large/delayed rewards. A significant difference in the impulsiveness score was detected between two chicken breeds (White Leghorn vs. Boris Brown; P < 0.01), as well as between White Leghorn chicks with different 5‐HTT genotypes. These findings imply the possibility that 5‐HTT VNTR genotypes may have some impact on chicks' impulsive choice by modifying the serotonergic neurotransmission.